FIRST INTERNATIONAL SYMPOSIUM ON AVIAN ENDOCRINOLOGY CALCUTTAJ JANUARY 10-15J 1977 PRESIDENT: DONALD S, FARNER - U,S,A, CONVENER AND ORGANISER: ASOK GHOSH - CALCUTTA EDITOR OF ABSTRACTS: BRIAN K, FOLLETT- U,K, PRINTED: UNIVERSITY COLLEGE OF NORTH WALESJ BANGORJ U,K,
CONVENER AND ORGANISER: ASOK GHOSH - CALCUTTA
EDITOR OF ABSTRACTS: BRIAN K, FOLLETT- U,K,
PRINTED: UNIVERSITY COLLEGE OF NORTH WALESJ BANGORJ U,K,
i
ACKNOWLEDGEMENTS
The Symp:>sium was sponsored by the Government of India, the
University Grants Commission of India, the University of Calcutta
and the Ramakrishna Mission Institute of Culture. The meetings were
held at the Birla Industrial & Technological Museum in
Calcutta. Grants-in-aid are gratefully acknowledged from the
Directorate of Education, Government of West Bengal, the Indian
National Academy of Science, the Kothari Scientific and Research
Institute and Organon (India) Ltd.
The local organising committee (Professor Asok Ghosh) are indebted
to the International Advisory Committee for their advice and
encouragement.
All the foreign participants are grateful to their respective
Governments and Scientific Councils for financial support.
EDITOR'S COMMENTS
The volume records, in the form of slightly extended abstracts, the
presentations given at the First International Symp:>sium on
Avian Endocrinology held in Calcutta during January, 1977.
Approximately 200 persons from 12 countries attended the meeting
and fifty-six papers were read covering most aspects of avian
endocrinology. Lectures which were intended to review a particular
field, and which lasted for 30 min., have been condensed into 3-5
pages while shorter communications have been limited to a single
page. Reprints have been provided to each author.
Many of the abstracts have been edited slightly and retyped to
improve their clarity. Any errors are the responsibility of the
editor.
INTERNATIONAL COMMITTEE ON AVIAN ENDOCRINOLOGY
During the meeting in Calcutta it was decided to form a small
Committee whose function would be to try and coordinate efforts in
avian endocrinology and possibly arrange future Symp:>sia. It
should be emphasised, however, that this informal committee has not
been set up in competition with more established organisations but
solely to help and I ink together !hose persons with an interest in
the hormones of birds. It includes the following persons: Chairman
- B. K. Follett (Department of Zoology, University College of North
Wales, Bangor, Gwynedd, U.K.), I. Assenmacher (Montpellier,
France), A. Epple (Philadelphia, U.S.A.), A. Ghosh (Calcutta,
India), E. Gwinner (Erling Andechs, Federal Republic of Germany),
S. Ishii (Tokyo, Japan), B. Lofts (Hong Kong), A. Oksche (Federal
Republic of Germany) and E. Skadhauge (Denmark). Should any person
require further information please do not hesitate to contact
either the Chairman or one of the Committee.
ii
CONTENTS
Presidential address: Time measurement in photoperiodic birds D. S.
Farner
Session I - General Organisation of the Avian Endocrine
Syste_m
Phylogenetic peculiarities of the avian endocrine system A.
Epple
Hormonal regulation of the uropygial gland S.P. Bhattacharyya, B.R.
Maiti &Asok Ghosh
Field investigations in avian endocrinology-methods and some
results John C. Wingfield & D.S. Farner
Histomorphology of the avian thymus S. Banerjee
Effects of hypercalcaemia on the ultimobranchial gland of pigeon,
Columba I ivia -- V. K~ Das & S. Das
Session II - Neuroendocrine Mechanisms
The neuroanatomical basis of avian neuroendocrine mechanisms A.
O~sche
The neuroendocrinology of photoperiodism in birds B. K.
Follett
Hypophyseal portal vessels in birds : A comparative study C.J.
Dominic
Potential sites and action spectra for encephalic photoreception in
the Japanese quail.
K. Homma, K. Sakakibara & Y. Ohta
Effect of hydrocortisone on the hypertonic saline-induced changes
in the hypothalamic neurosecretory system of the spotted owlet,
Athene bromo, Temminck --- --
K.B. Singh
Sess1on Ill - Physiology of the Pineal Body
Role of the pineal in the control of circadian and circannual
rhythms in European starlings
E. Gwinner
Pineal and the neuroendocrine basis of reproduction in birds R.N.
Saxena
2
7
10
13
15
16
17
20
23
25
27
28
30
iii
Role of pineal and photoperiodism in the hypothalamo-hypophyseal
gonadal axis of weaver bird
K.S. Balasubramaian
Pancreatic control of avian carbohydrate metabolism R.l.
Hazelwood
The role of glucagon in birds P. Mialhe, G. Sitbon, C. Foltzer, E.
Krug, R. Gross & F. Laurent
Effect of two oral hypoglycaemics on the blood sugar level, adrenal
medulla and cytology of the endocrine pancreas of pigeons
B. Guha
Cholinergic assistance to the release and action of insulin in
pigeons B. Pilo, P. V. Patel & R. V. Shah
Evidence for a non-pancreatic source of chicken insulin R.l.
Hazelwood & J.R. Colca
~':ssion V - Developmental Endocrinology
Ontogeny of corticosteroid receptors in chick embryonic kidney J.G.
Lehoux, C. Beaudry & D. Bellabarba
Aminoglutethimide phosphate-induced inhibition of cortical tissue
in chick embryonic gonads
J.S. Knight
Influence of hypothyroidism on histophysiology of feather
development R.V. Shah, G.K. Menon & B.M. Jani
Effect of methyl-thiouracil and T 3 on the CNS of chick embryo K.
Chandrasekhar, G.N. lv10skovkin & M.S. Mitskevich
Transformation of the female right gonad of the fowl into a fertile
testis M. T. Frankenhuis
Session VI -Mechanisms of Honnone Action
Gonadotropin receptors in the avian testis S. Ishii
Corticosteroid receptors in avian tissue L. Charest-Soule, A.Z.
Mehdi & T. Sandor
The action of avian LH on androgen secretion from the interstitium
of the avian testis
Z.W. Maung, S.L. Maung & B.K. Follett
Hormonal regulation of certain enzymes of L-ascorbic acid
metabolism in chicks
A. Bhattacharyya
Proc. First lnternatl. Symp. Avian Endocrinolo•Jy, Calcutta, Jan.
1977
iv Session VII - Reproduction
Endocrine aspects of ovulatory cycle of the domestic fowl. K.
Tanaka
Photoperiodic responses of Indian birds A. Chandola & J.P.
Thapliyal
Adrenal sex-steroidogenesis in caponised domestic pigeon, Columba
Iivia ----
--R.N. Mukherjee & A. K. Sarkar
Effect of ext ern a I gamma irradiation on the testis of the house
sparrow, Passer domesticus (Linn.). --O.K. Vyas & D.
Jacob
Endocrinology of avian Sertol i cells B. Lofts
Differences in the endocrine mechanism of ovulation of the domestic
fowl and the Japanese quail.
Y. Tanabe
Effects of avian and mammal ian pituitary materials on ovarian
function in the hen.
K. lmoi
M. Wodo, K. Wakabayashi, T. Adachi & S. Ishii
Steroid synthesizing cellular sites in the developing gonads of the
domestic pigeon, Columba Iivia.
B. V. Bhujle & V~B.No::lkarni
Photoperiodic induction of gonadotrophin release in quail on the
first long day.
B. K. Follett & D. T. Davies
Effect of Sodium malonate, on inhibitor of TCA cycle on spermato
genesis in hens.
C. Deb, G. Mojumder, P. Koul & N. Mollik
Some observations on steroid dehydrogenoses in the avian ovary.
P.M. Ambodkor & V. C. Kotok
Polysaccharide cytochemistry of the duck oviduct. D. Pol
Session VIII - Salt G1ond Function
57
60
63
64
65
68
71
75
76
77
78
79
80
81
v
Pituitary control of avian adrenal function W.N. Holmes
Adrenocortical functions in birds T. Sandor & A.Z. Mehdi
Mechanism of release of catecholamines from the adrenal medulla of
fowls.
S. Subrahmanyam & M. Quadir
Relationship between adrenal and gonadal cycles. C.M. Chaturvedi
& J.P. Thapliyol
A comp:::~rative survey of the interrenal tissues of some avian
species. C.K. Manna
Adrenal response to crowding in parakeet, Psittacula kromari. J.
Banerjee --------
Cytochemical study of odrenomedullary mucopolysocchorides in an
avian species, Pholacrocorax niger.
D. Bhakta---------
_5essio~ X - Thyroi~ and Paro!~rr..?~~~lond~
Role of parathyroid hormone on renal excretion of calcium and
phosphate in the European starling.
N.B. Clark & R. F. Wideman
Effect of thyroidectomy on the premigratory adaptive
hyperlipogenesis in the migratory starling Sturnus roseus.
R.V. Shah, S.T. PoteT&B.Pi1o
~essi~~-~:_nal Endo~rinologr_
Drinking induced by angiotensin in birds. H. Kobayashi, Y. Takei,
H. Uemura & M. Woda
The avian renin-angiotensin system H. Sokabe
Hormonal control of avian osmoregulation. E . Skadhauge
A biochemical-histochemical investigation on the effect of
vasopressin on the avian kidney.
D.N. Kamat, M.M. Kothari, P.V. Deshponde, S.D. Sontakke, R. P.
Athalye & K. G. Chacko
Cytology of the avian juxtaglomerular apparatus. D. Ghosh
85
88
91
92
93
94
95
96
97
98
101
103
106
107
Proc. First lnternatl. Symp. Avian Endocrinology, Calcutta, Jan.
1977 ?roc. First lnternatl. Symp. Avian Endocrinology, Calcutta,
Jan. 1977
Vote of thanks A. Oksche
Author Index
108
109
1
University of Calcutta, India.
Avian endocrinology concerns the study of endocrine glands in
diverse
species of birds, including poultry, game and wild. The prime
academic objective of this subject is to reconstruct evolutionary
pathways by the study of living avian species. Apart from
contributing to the over all phyletic study, we also aspire to
rebuild the lines of evolution
within the endocrine system itself taking both morphological and
functional criteria in our account. We can concern ourselves with
the molecular evolution of hormones, with the prcbable
acquisition
of new active sites conveying new properties and finally explaining
the mechanism of hormone action in terms of receptor protein
and
consequent genetic effects.
The provision of the academic aims is not however, sufficient
justifi cation for the men with a more materialistic outlook. The
applied avian endocrinology is the answer to them. The process of
reproduc tion in birds, like other group of vertebrates, is
dependent on the
hormonal secretion and an understanding of this relationship can
provide information that may be usefully applied when, for economic
reasons, vve may wish to increase, or control, the fecundity of a
species. Aithough there is a respectable endocrinology of the
poultry birds
(particularly the chicken and not so much on the duck) there has
been but rather restricted concern with potentially egg and meat
producing
wild birds. Regarding the birds of agricultural importance, we must
attempt to prepare an inventory, to determine which birds does
harm, which is beneficial, and which is of neutral status ; thus as
to which
species should be encouraged near the agriculture and which should
be discouraged. In near future, we hope a full fledged discipline
of 'Economic Ornithological Endocrinology' will emerge out and
would
prove particular significance to the cause of developing
countries.
The first international seminar on a somewhat specialized aspect
of
avian endocrinology (hypothalamic function and avian reproduction)
was held in -.Japan sometime in 1 969, under the able leadership of
Professors Farner and Kobayashi. After the great success of this
seminar, some of us started thinking whether holding an
international
symposium is possible encompassing multiple aspects of the avian
endocrinology. -.Just about two years ago from now I had the
fortune of meeting here in Calcutta three topmost avian
endocrinologists like Professors Farner, Kobayashi and Assenmacher.
They all enthusias
tically agreed to the proposal and with their approval we
approached
other distinguished scientists of the field and their response was
also tremendous. With this decision we started organising which
resulted in the present symposium. This, in brief, is the genesis
of the First International Symposium on Avian Endocrinology.
Proc. First lnternatl. Symp. Avian Endocrinology, Calcutta, Jan.
1977
2
FARNER, D.S.
Department of Zoology, University of Washington, Seattle,
U.S.A.
More than a half century has now elapsed since the first
experimental demonstration by Rowan of the use of day length as
information in the control of annual cycles. It is now clear that
the use of some part of the annual photocycle as information for
control systems is widespread among species of mid- and high
latitudes. The extensive investigations on avian photoperiodism
have had at least three basic often overlapping motivations: (1) To
understand the basis of the temporal adjustment of reproductive and
related functions of birds to the most favorable phases of annual
environmental cycles. (2) To increase knowledge of the temporal
organization of life in terms of the interaction of endogenous
periodicities with both periodic and aperiodic changes in
environmental conditions, (3) To provide a basis for under
standing better the general scheme of control of reproduction in
higher vertebrates. The rationale for the last is simple since the
organs and hormones involved are very similar among these classes
of vertebrates. The photoperiodic species of birds offer unique
research opportunities since there are quantitatively predictable
relationships between input into the system, day length, and
output, plasma levels of gonadotropins and sex hormones, and
gonadal growth and function, The important experimental opportunity
of setting precisely the rates of gonadotropic functions by simple
manipulation of day length remains relatively unexploited.
The literature on avian photoperiodism, at least superficially,
presents elements of confusion. In part this confusion has been
generated by differences among the conceptual frameworks in which
investigators have designed experiments. Further confusion has
resulted from a failure to recognize substantial specific
differences in control systems, doubtless due, in part, to multiple
evolutionary origins.
Among the photoperiodic species that have been subjected to careful
quantitative investigation growth of testes under constant
stimulatory day lengths closely approximates a logarithmic function
of time until about half of maximum size is attained; furthermore,
the logarithmic growth-rate constant is a positive function of the
duration of the daily photophase although this function differs
among species. Although information is somewhat fragmentary it
seems clear that there are quantitative relationships between day
length and the plasma level of gonadotropic hormones.
These quantitative relationships indicate that the control system
must have a chronometric function, The basis for this chronometric
function in at least some photoperiodic birds appears to be an
external coincidence timer, the concept of which was first proposed
by BUnning in 1936 and subsequently refined by
Proc. First lnternatl. Symp. Avian Endocrinology, Calcutta, Jan.
1977
3
Pittendrigh and Minis in 1964. Simply stated, the hypothesis
proposes the occurrence in the control system of a circadian
periodicity in photosensitivity that is entrained by the daily
environmental photocycle. The rate of the photoperiodic response is
a positive function of the time during which the environmental
photo phase is coincident with the photosensitive phase of the
oscillation in photosensitivity.
This hypothesis has been tested in photoperiodic species by three
general types of experiments: (1) Scotophase-scan experiments. In
such experiments birds have usually been subjected to a basic daily
photophase of six or eight hours, in itself non-stimulatory. Each
experimental group receives each night, at a different time for
each group, a short photophase. The response has been measured in
terms of increase in gonadal weight. The results have generally
shown that the short photophases become increasingly effective
through the course of the first part of the scotophase and then
decreasingly effective during the latter part. These results have
in general been interpretable as demonstrating an entrained
oscillation in photosensitivity that accounts basically for the
increase in the logarithmic growth rate as a function of the length
of the daily photophase, However, because the experimental birds
must be subjected to many cycles there are problems of entrainment
and questions about the precision and interpretation of the
results. (2) Resonance experiments. In its most common form groups
have been subjected to lighting regimes of (a) sL (24-s)D, sl
(48-s)D, sL (72-s)D ... and (b) sL (36-s)D, sl (60-s)D, sL (84-s)D
... , where the photophase s is non-stimulatory, i.e.' 8 hours
or-less, in a 24-hour cycle. -The external coincidenc~ model
predicts that repetition of the regimes in series b should be
s~imulatory whereas those in series a should be non-stimulatory.
This has been generally confir~ed by experiments on at least five
species. However, as the duration of the scotophase is increased,
the gonad weights in a and b tend to converge suggesting problems
of entrainment~ (3)-Single-stimulus experiments. The development of
a microradioimmunoassay for avian luteinizing hormone by Professor
B.K. Follett and his colleagues permits experiments that avoid the
difficulties of entrainment encountered in the scotophase-scan and
resonance experiments. In Zonotrichia leucophrys gambelii a single
photophase coincident with the photosensitive phase causes a three
to five-fold increase in the level of luteinizing hormone in the
plasma (Follett, B.K., Mattocks, P.W., and Farner, D.S., Proc. Nat.
Acad. Sci. 71, 1666. 1974); similar results have been obtained--
with CotUrnix coturnix (Follett, B.K., and Davis, D.T., ~· Zool.
Soc., London 35, 199. 1975). This has permitted experiments in
which a single photophase applied at selected intervals to
individual birds held in continuous darkness for 12 to 108 hours
(Follett et al., ibid,). The results indeed show an approximately
24-hour osciTTation between photosensitive and non-photosensitive
phases. However, this kind of experiment cannot define rigidly
photosensitivity as a function of time.
An interesting further test is provided by the unusual
relationship
Proc. First lnternatl. Symp. Avian Endocrinology, Calcutta, Jan.
1977
4
between day length and the rate of testicular growth in Passer
domesticus in which day lengths longer or shorter than 6~ours cause
growth of the testes. Dolnik (In "Fotoperiodizm zhivotnik rasteni i
," O.A. Scarlato, ed., Akademia Nauk SSSR, p. 47. 1976) has
proposed an explanation for both the long-day and very-short day
responses on the basis of a two-oscillator {internal coincidence)
model. This model assumes that one oscillator is entrained by
"lights on" and the other by "lights off." Photoperiodic responses
occur when the phase angle between the two is relatively great.
Recently we {Farner, D.S., Donham, R.S., Mattocks, P.W., Lewis,
R.A., Darden, T.R., and Smith, J.P., Physiol. Zoo!., in press) have
demonstrated that the very short-day responses are consistent with
a simpler external coincidence model. On very short daily photo
phases the phase of the photosensitivity oscillator apparently
advances so that the photosensitive phase becomes coincident with
the environmental photophase.
Internal coincidence models as the basis for photoperiodic control
systems in birds have been discussed in a general sense by Gwinner
{~. Repr. Fertil. ~. 19, 51. 1973). Schwab and Rutledge {Cong.
Intern., "Le Solei! au Service de !'Homme." UNESCO. p. B. 15-1.
1973) have suggested that such a system may be involved in gonadal
development in Sturnus vulgaris in continuous darkness. It is clear
that the photoperiodic control system of this species differs
conspicuously from that of most photoperiodic avian species. I find
it difficult, at the present state of our knowledge, to rationalize
it in terms of mechanisms established for other species although
the existence of a circennial cycle appears to be established
{Schwab, R.G., in "Biochronometry," M. Menaker, ed. p. 428. Nat.
Acad. Sci. 1971; Gwinner, E., cited above). The available data
argue strongly in support of a hypothesis of multiple origin of
photoperiodic controls of gonadal function among birds.
Professor A.H. Meier and his colleagues (~·.9.·• Meier, A.H. In
"Proc. XVI Int. Ornithol. Congr. ," H.J. Frith and J.H. Calaby,
eds, p. 355. Austral ian Acad. Sci. 1976) have developed a complex
model to rationalize the annual cycle of the photoperiodic
White-throated Sparrow, z. albicollis. Basically, this model
depends on seasonal changes i;:;- the phase angle between
"circadian rhythms" in the plasma levels of corticosterone and
prolactin, the latter inferred from assays of pituitary prolactin
and experiments involving injections of mammalian prolactin. It
involves inferences concerning photo-inducible phases in secretion
of LH, FSH and prolactin without direct measurement of the plasma
levels of the hormones, and a "circannual" rhythm of change of
phase of a circadian oscillator. In our more conservative approach
to the system of the closely related I· leucophrys we have been
unable to confirm the assumptions on which the Meier model is
based. However, we in no sense at this time argue for its rejection
but urge that it be rigidly tested.
Another possible mechanism in the chronobiological basis of
photoperiodic controls is the hourglass timer. Although I
have
Proc. First lnternatl. Symp. Avian Endocrinology, Calcutta, Jan.
1977
5
often considered this type of mechanism in a model for z.
leucophrys, I have set it aside because of the evidence-for, and
attractiveness of, a relatively simple external coincidence model.
However, the possibility that both may occur in an avian control
system should not be overlooked.
Following the impetus of the important review of Aschoff (Stud.
Gen. 8, 742. 1955) substantial evidence for the occurrence of
endogenous circennial periodicities among birds has been
accumulated (~·.9.·• Berthold, P., Voaelwarte 28, in press, 1977;
Gwinner, E., ibid.). There is for no less than ten species
acceptable evidence for such cycles in molt, migratory behavior or
gonadal development. Such periodicities must be regarded as real or
potential components of temporal organization although further
information is needed to assess their nature, general occurrence
and role in natural annual cycles. Like endogenous circadian
periodicities, endogenous circennial cycles have periods, that
differ from the period of the annual environmental cycle, usually
being shorter. Thus, whatever role such periodicities may have in
the temporal organization of natural annual cycles requires a
Zeitgeber with a precise annual frequency. This raises the question
as to whether photoperiodic systems drive annual cycles or serve an
entraining mechanism for endogenous cycles and Gwinner (1973, cited
above) argued.
I agree that for at least some species a hypothesis, that annual
cycles are endogenous circennial periodicities entrained by
environmental Zeitgebers with annual periods. It provides an easier
rationalization for annual cycles in which day length has no
obvious role and perhaps also for the annual cycles of trans
equatorial migrants. What must have been learned about photo
periodic control systems is, in general, whether these systems
function as drivers as synchronizers. Nevertheless, beyond the
precarious assumption that the annual cycles of all species that
have such, conform to a single system, there are other reasons for
caution, at least in the present state of our knowledge.
With the exception of the irregular cycles in domestic mallards
held in continuous light or dark demonstrated in by Professor
Jacques Benoit and his colleagues, the demonstrationsof endogenous
circennial cycles have been effected under conditions involving
24-hour light-dark cycles. Although I agree that continuous light
and continuous darkness are very unnatural conditions, this does
remove certain doubts about the nature of these cycles since the
recurrence of light in a 24-hour cycle may be, in itself, a source
of environmental information. Indeed, at least in Zonotrichia
leucophrys this seems to be the case.
As demonstrated by Gwinner (1973, cited above) for Sturnus vulgaris
and by Wolfson (1. ~· Zool. 125, 353. 1954) for Junco hyemalis and
I· albicollis, manipulation of the photoperiodic environment can
result in several cycles within the course of a year. Jf these are
entrained endogenous circennial cycles one is forced to assume that
the basic oscillator has an unusually labile
Proc. First lnternatl. Symp. Avian Endocrinology, Calcutta, Jan.
1977
6
period, so unusual as to raise the question as to whether it indeed
has the characteristics of an oscillator. These comments are made
not to challenge the existence of endogenous circennial
periodicities. Rather, they are intanded to serve as a reminder
that adaptations of control systems for the exploitation of an
annually periodic environment may •,o~ell be too diverse and of too
many origins to fit a general hypothesis that requires an
endogenous circennial oscillator. Many phenomena ascribable to an
endogenous circennial periodicity can be explained by assuming that
the control system has a natural period of about one year (King,
J.R., and Farner, D.S. In "Chronobiology" L.E. Scheving, F.
Halberg, J. E. Pauly, eds. p. 625. lgaku Shoin, Tokyo. 1974) just
as a motionless pendulum has a fixed period. External information,
such as some phase of the-annual photocycle, ~·~· vernal increase
in day length, or the "constant conditions" of continuous 12L 120
could release internal energy that causes oscillation in accordance
with the natural period of the system. The performance of the
system subsequently would depend in part on its damping
characteristics. If the damping constant is high the system would
appear to be one in which the photoperiodic control scheme has a
driving function; if it is low it would be one that would
characterize the endogenous circennial cycles in the several
species of warblers investigated by Bertho I d and his co II eagues
( 1977, cited above). As I have argued earlier, and as expressed
much more eloquently, and with much more data, by Dolnik (1976,
cited above), the use of day length as environmental information in
the photoperiodic species is confined to one, or at most two,
restricted components of the annual cycle. The remaining components
appear to be natural sequelae of those controlled by the
photoperiodic system. Thus the question of the role of day length,
as a driver or synchronizer may become a matter of interpretation
or even of semantics. I urge that we not attempt prematurely to
force our fragmentary information into a single
"comprehensive hypothesis. Selection in evolution has been on
systems that enhance survival, not on their origins and prior
histories.
Proc. First lnternatl. Symp. Avian Endocrinology, Cal~utta, Jan.
1977
. I
7
Phylogenetic peculiarities of the avian endocrine system
Introduction. It appears a tacit assumption that a high rate of
intermediary metabolism should be accompanied by sophisticated
neuro-endocrine control mechanisms. Along this line of reasoning,
one would expect the birds to possess a particularly well-developed
endocrine system. In the following it will be tried to test this
assumption, paying particular attention to three endocrine systems
which show obvious phylogenetic variations: the pineal complex, the
hypothalamo-hypophysial system and the islet organ.
Phylogenetic Distribution of Vertebrate Endocrines. The attempt to
correlate the total number of endocrines with the rate of metabo
lism, particularly with homeothermia shows that neither birds nor
mammals have the largest number of endocrines. The largest number
of endocrines is actually found in the teleosts. This group pos
sess~ all classical endocrine glands ever developed in vertebrates
with the exception of the parathyroid, which is restricted to the
tetrapodes. On the other hand, we find in birds a reduction of the
components of both the pineal complex and of the hypothalamo
hypophysial system, and a s.implification of the control mechanism
of the pancreatic islets. Thus, the conclusion is inevitable that
phylogenetically a high rate of intermediary metabolism and a
sophisticated endocrine control system are by no means connected.
The simple endocrine system of the Myxinidae shows that there is no
connection between a low rate of intermediary metabolism and a
well-developed endocrine-sjstem either.
The Pineal Complex. As a derivative of a pair of frontal eyes
(Eakin, R.t1. (1973): The third eye. University of California Press
Berkeley) this structure shows a phylogenetic trend to develop into
a receptor-secretor complex which transfers light stimuli into
endocrine secretion. Along this way the anterior eye (Parietal
organ, Parapineal organ) retains its photoreceptor function while
the posterior eye {Epiphysis cerebri, Pineal gland) seems to
specialize increasingly in endocrine secretion. Quite frequently,
the parapineal organ disappears completely. However, since it is
still a rather well-developed frontal eye in certain lizards and in
Sph~noion, it must have persisted in the ancestors of the birds
"up" to the reptilian level. At this stage, the parietal organ
controls the deeper situated and mainly endocrine pineal gland via
its Nervus pinealis, though the pinealocytes themselves can still
respond to light stimuli. In addition, the pineal is innervated by
sympathetic fibers, arising from the superior cervical ganglion,
and humoral stimuli may also have an effect. Furthermore, the
pineal gland conveys nervous messages to the CNS via its Tractus
inealis, thus possessing both nervous and endocrine function Ueck,
M. (1974): Fortschr. Zool. 22:167-203). In summary then,
the reptilian ancestors of the birds must have had a
well-developed
Proc. First lnternatl. Symp. Avian Endocrinology, Calcutta, Jan.
1977
8
pineal complex whose endocrine component, the pineal gland, was
under dual nervous control (Nervus pinealis and Sympathicus); in
addition direct photic and humoral stimuli may have had an effect
on its function, which was exerted via hormonal and nervous
signals.
In birds, the parietal organ has disappeared, and even the pineal
gland may be absent in some species (Ralph, C.L. (1970): Amer.
Zool. 10:217-235). The outer photosensitive segment of the
pinealocytes is almost as strongly reduced as in mammals, and the
Tractus pinealis shows no response to phototimulation of the pineal
gland. This leaves us only with one clearly established control
mechanism, i.e., the sympathetic innervation. However, one might
speculate that humoral factors (hormones?) and perhaps still some
direct light stimuli have an effect on the avian pineal. Physio
logically, the avian pineal gland remains largely an enigma.
Neither pinealectomy nor interruption of its possible neural photo
periodic control system (via pineal transplantation, denervation or
removal of the eyes) seem to have an effect on gonadal activity,
though all of these procedures strongly influence the gonads of
mammals. So far, the only clear physiological effect of the avian
pineal was shown by Menaker and coworkers (Menaker and Zimmerman,
1976) who found that the gland is essential for the maintenance of
the circadian motor activity of Passer domesticus. Though the poor
development or even complete absence in various vertebrates suggest
that the pineal complex is phylogenetically one of the most
"disposable" endocrine structures, its poor development in the
generally very photosensitive birds is remarkable. The most
plausible explanation we could come up with was that it was already
reduced in the archosaurian ancestors of the birds {Epple, A. and
M.H. Stetson (1976): J. Ormithol. DI.:257-278).
The Hypothalamo-Hypophysial System. The activities of the adeno
hypophysis are largely controlled by two central nervous
mechanisms: (1) Neurohormones, released into the hypophysial
portal'·· circulation, and (2) direct innervation. Neurohormonal
control is the prevailing mechanism controlling the Pars distalis,
while direct innervation seems to be important for the function of
the Pars intermedia (in almost all species). A control of the Pars
distalis (via direct innervation) occurs in the teleosts, and to
some extent also in lungfishes. Obviously, this indicntes the need
for fast and/or private signals (For lit., see Epple, A. and J.E.
Brinn (1975): Gen. Comp. Endocrinol. 27:320-349). A Pars inter
media seems to exist in all gnathostomes below the ammiotes. In the
latter group its size varies greatly even between close relatives,
and it is even absent in some species (Wingstrand, K.D. (1966): In:
The Pituitary Gland (eds. G.W. Harris & B. T. Donovan,
Butterworths, London), Vol. 1:58-126.). The birds are the only
larger phylogenetic group in which a Pars intermedia is totally
lacking. Thus, at a first glance, the hypothalamo-hypophysial
system of the birds appears rather simple. However, one feature of
the avian hypothalamo-hypophysial system seems to be unique: the
subdivision of the Median eminence into an anterior and a posterior
portion. Each of these port1ons 1s largely drained into a
Proc. First lnternatl. Symp. Avian Endocrinology, Calcutta, Jan.
1977
9
corresponding portion of the Pars distalis, the cephalic and caudal
lobe, respectively. The evolution of this system from the general
reptilian type is difficult to understand as long as one assumes
that specific neurohormones control specific target cells scattered
throughout the Pars distalis. However, if one assumes that a single
neurohormone controls two topographically separated cell types with
different secretory patterns, then this system makes sense. We have
therefore suggested that it may reflect the control of two types of
gonadotropes (each of which is restricted to a particular lobe
only) by a single releasing factor {Epple & Stetson, 1976).
Clearly, this hypothesis requires further support from data which
confirm (a) the presence of two types of gonadotropes in birds, and
(b) the presence of a single releasing factor controlling both of
them. However, since the avian pattern of egg laying requires a
highly sophisticated tempor·al coordination of hormonal secretions,
and since this pattern must have developed from the simple simul
taneous oviposition of the reptiles, our hypothesis appears
reasonable.
Pancreatic Islets. The i ;let organ of all gnathostomes produces at
least 4 different substa~cPs, of which insulin, glucagon, and pan
creatic polypeptide are generally recognized as true hormones. The
hormonal status of Somatostatin, (found in the D-cells) may yet
require further studies (Fpple, A. & J.E. Brinn (1976): In: The
Evolution of the Pancreatic Islets (Grillo et al., eds.) Pergamon
Press, Oxford). The parti ':ular features connected wi tl1 the
avian islet organ are (Hazelwood, R.L. (1976) and Epple, A. &
J.E. Brinn (1976): In: The Evolution of the Pancreatic Islets
(Grillo et al., eds). Pergamon Press, Oxford): ( 1) a very high
percentage of glucagon-producing A-cells end D-cells, {2) a strong
separation of A- and B- cells which occur largely in different
types of islets, (3) the virtual absence of a secretomotor islet
innervation, (4) the insulin-insensitivity of the avian adipose
tissue (which, however, also occurs in the eel and probably other
teleosts). The evolutionary significance of these features, which
are in contrast to those of the mammals, is difficult to explain
with respect to homeothermia. However, it is noteworthy that, as in
the case of the adenohypophysis, the islet innervation reaches its
peak in the teleosts (Epple & Brinn, 1975).
Conclusions. From the preceeding it is clear that the high rate of
intermediary metabolism of the birds is by no means accompanied by
a sophisticated endocrine system. The probably most remarkable
endocrine peculiarity of the birds, i.e., dualism of the adena
hypophysial blood supply, may be related to the reproductive
function, particularly of the female bird. The reasons for the
morphological and physiological peculiarities of the avian islet
organ are unclear. The poor development of the avian pineal complex
may be an irreversible heritage from reptilian ancestors.
Proc. First lnternatl. Symp. Avian Endocrinology, Calcutta, Jan.
1977
10
* ** ** BHATTACHARYYA, S.P. , MAITI, B.R. AND GHOSH, ASOK
* Department of Zoology, University of Kalyani, Kalyani, India and
** Histophysiology Laboratory, Department of Zoology, University of
Calcutta, Calcutta 700019, India.
This review attempts to point out the role of endocrine factors in
the regulation of the uropygial gland, an organ whose exact
fUnctions are not known. Earlier reports concerning its role in
plumage maintenance, its assistance in buoyancy in water, in growth
and in vitamin D production have yet to be confirmed (Elder, W.H.,
The Wilson Bulletin, 66, 6, 1954).
From histomorphological and cytochemical standpoints there exist
basic similarities between the uropygial gland and the mammalian
sebaceous gland (Das, M. and Ghosh, Asok, Anat. Anz., 1Ql, 75,
1959; Bhattacharyya, S.P. and Ghosh, Asok, Acta histochem., .Ji,
318, 1971; Bhattacharyya, S.P., La Cellule, &i, 111, 1972).
Maintenance of both these holocrine structures is accomplished by a
reciprocally synchronized balance between constant cell supply
through mitotic division, and cell elimination (Maiti, B., Folia
Biol., 1£, 49, 1968). The secretions from the uropygial gland are a
complex mixture of different lipid classes, in which wax esters
constitute the major component. The glands of Galliform birds,
which have been examined so far, secrete diester waxes with long
chain 2,3-n-alkane diols (uropygiols), which are of rare occurrence
in animal tissues (Haahti, E. and Fales, H.M., J. Lipid Res.,~.
131, 1967; Saito, K. and Gamo, M., J. Biochem., £1, 841, 1970;
Nikkari, T., J. Invest. Dermatol., 62, 257, 1974.
The structure and the secretory activity of the uropygial gland are
influenced by endocrine factors and our knowledge at this stage is
limited only to sex hormones and corticosteroids. Androgens are
potent stimulatory agents for this gland. Hyper secretory
conditions of the gland in the male house sparrow (Passer
domesticus) coincides with the enhanced testicular activity during
the breeding phase of the gonadal cycle of this bird (Maiti, B.,
Proc. Zool. Soc. Calcutta, 22, 87, 1969). Although chronic
administration of testosterone caused a mild depression in the
weight of the uropygial gland in cockerels (Selye, H., J. Morph.,
ll• 401, 1943; Kar, A.B., Anat. Rec., ~. 75, 1947), this steroid
elicited a marked stimulation in the alveoli of the gland in adult
pigeons (Maiti, B.R. and Ghosh, Asok, Gen. Comp. Endocrinol., 12..
527, 1972). This effect resulted from an acceleration in cell
renewal, cell differentiation and cellular desquamation, as well as
by an increase in lipid production. Bilateral castration in pigeons
and ducks resulted in atrophy of the uropygial gland by a decrease
in the rate of cell multiplication and cell growth. Castration in
pigeons also impeded release of the secretory materials from the
gland. In ducklings and prepubertal pigeons the effect of
castration was found to be more severe than that in adult
specimens.,, Testosterone therapy of the castrates restored normal
physiological conditions in the uropygial gland.
Proc. First lnternatl. Symp. Avian Endocrinology, Calcutta, Jan.
1977
11
Like the preputial gland and the skin of 1111U11118.ls, the
uropygial gland tissue of the domestic duck is capable of binding
testo sterone. Experiments using 3H-testosterone have revealed the
presence of an androgen-specific receptor protein in the nuclear
fraction of the gland. Further, it has been shown that the
uropygial gland of dude and chick can convert testosterone into the
tissue-active androgen, 5o( -dihydrotestosterone, at a fairly high
rate like other androgen-sensitive organs. These findings not only
furnish another line of evidence for the positive in fluence of
testosterone on the uropygial gland but also indicate some of the
early metabolic events of androgen action within this organ (Loeb,
P.M. and Wilson, J.D., Clin. Res., jl, 45, 1965; Wilson, J.D. and
Gloyna, R.E., Res. Progr. Hormone Res., 26, 309, 1970).
The influence of oestrogens on the uropygial gland is not clear.
Diethylstilboestrol tre:ttment was found to be ineffective in in
ducing any alteration in the gland of intact or castrated white
Leghorn cockerels (Kar, A.B., Anat. Rec., ~. 75, 1947), while
administration of oestr3diol to male pigeons provoked weight loss
of the gland and regression of the alveoli (Maiti, B.R., Arch.
histol. jap., ,ll, 371, 1971). Alveolar atrophy was shown by
excessive cell loss (with a concomitant fall in the cell renewal
rate), decreased output of lipids and augmented levels of acid
phosphatase. In contrast, in female juvenile spotted munia
(Lonchura punctulata, L.) exogenous oestradiol brought about
hypertrophy of the uropygial gland (Kar, A.B., Nature, ~. 495,
1949). In adult fe'lla.le pigeons this steroid caused pronounced
alveolar hyperplasia associated with increased cell loss. These
results indicate rather a sex-specific action of oestrogens. Since
spaying either prepubertal ducks ~~d pigeons or postpubertal
pigeons could not induce any recognizable effect on the glandular
activity, it is assumed that oestrogen is not involved in the
maintenance of the uropygial gland (Maiti, B.R., Arch. histol.
jap., ,ll, 371, 1971).
Similarly, any direct action of progesterone on this gland can be
ignored, as the luteoid, when administered to castrated pigeons at
a dose of 1.0 mg daily for 15 days, failed to prevent the glandular
atrophy which resulted from castration (Maiti, B.R., Monitore Zool.
Ital. (N.S.), ~. 11, 1972). The observed simulatory action of a low
dose of progesterone on the gland of intact adult male pigeons
(Bhattacharyya, S.P. and Ghosh, Asok, Folia Bioi.,~. 89, 196o)
might have been mediated through en hanced androgen release.
A direct role for the adrenals in the maintenance of the uro
pygial gland has not yet been fully elucidated. Cortisone loading
in male pigeons induces consistent hyperactivity of the gland. This
has been assessed from cytodynamic and histochemical findings
(Maiti, B. and Ghosh, Asok, Acta anat., ]k, 97, 1969}.
Proc. First lnternatl. Symp. Avian Endocrinology, Calcutta, Jan.
1977
12
Inhibition of endogenous corticosteroid production by metopirone
(SU 4885) led to degeneration of the alveoli (Bhattacbaryya, T.K.
and Ghosh, Asok, J. Morph., jjQ, 257, 1970). These studies indicate
a possible involvement of glucocorticoids in the regu lation of
the uropygial gland.
It appears that the response of the uropygial gland to male and
female sex hormones is identical to that of the sebaceous gland but
the role of other (extra-gonadal) hormones on its function is still
unknown.
Proc. First lnternatl. Symp. Avian Endocrinology, Calcutta, Jan.
1977
13
WINGFIELD, J.C. AND FARNER, D.S.
Department of Zoology, University of Washington, Seattle,
U.S.A.
Methods have been developed (Wingfield and Farner, Condor 78, 570.
1976) for collection of blood samples, and preparation and
transport of plasma from feral populations of White-crowned
Sparrows, Zonotrichia leucophrys. Adults of both sexes as well as
birds of the year were captured in Potter traps or mist nets,
color-banded, blood samples taken and then released for subsequent
observation and recapture. Tape-recorded song was used to lure
birds into mist nets. Notations of body weight, fat depot, brood
patch and molt were also made. Laparotomy was performed in most
cases to determine the state of development of the reproductive
system. Blood samples were centrifuged in the field and plasma
stored and transported frozen on dry ice. Our data and observa
tions indicate that the capture and processing procedures were not
sufficiently stressful to delay or otherwise disrupt the breeding
cycle.
A fraction of each plasma sample was used for measurement of
luteinizing hormone (LH) by a double-antibody radioimmunoassay
(Follett, B.K., Scanes, C.G., and Cunningham, F.J., J. Endocrinol.
52, 359. 1972; Follett, B.K., Farner, D,S,, and Mattocks:-Py-;
Gen. Comp. Endocrinol. 26, 126. 1975). The remainder was used for
the simultaneous measurement of 171f-hydroxy-5ot-androstan-3-one
(DHT), testosterone, estrone, and estradiol-17~ by radioimmunoassay
(Wingfield and Farner, Steroids 26, 311. 1975) and corticosterone
by a competitive protein-binding assay (ibid,) after chromatography
on Celite microcolumns. ----
Plasma levels of these hormones were correlated with the
reproductive cycle of a multiple-brooded, short-distance migrant,
I·l· pugetensis, that breeds in the Puget Sound area at 48°N,
Plasma immunoreactive LH (irLH) and testosterone reached the
highest levels in males in spring during courtship and nesting
preceding the first clutch. A smaller second maximum in irLH was
observed in males at the time of the second brood, but there was no
increase in testosterone, In contrast, the females showed equal
maxima in plasma irLH, DHT and estrone during ovulation and ovi
position for both broods, Plasma testosterone was lower during the
second brood and estradiol-17p increased to a maximum during
vitellogenesis in the first brood but not the second.
The gonads and secondary reproductive organs of both sexes during
the second breeding period recrudesce to the same level of
development as attained during the first. Plasma corticosterone
increased gradually throughout the breeding season reaching a
maximum in both sexes during the time of the second brood. Titers
of all hormones measured decreased to basal levels during
Proc. First lnternatl. Symp. Avian Endocrinology, Calcutta, Jan.
1977
14
post-nuptial molt.
The maximum level of testosterone in both sexes occurred at the
time of territorial defense before the laying of the first clutch.
The maximum level in males was approximately seven times as great
as that in the females. The latter defend territory during this
period but less extensively than do the males. In both sexes there
was an increase in the ratio of irLH to testosterone throughout the
season. This relationship has been observed in ~·l· gamb~ during an
experimentally induced testicular cycle (Lam, F., and Farner, D.S.,
Cell Tiss. Res. 169, 93. 1976) and in a breeding population in
Alsaka (Wingfield and Farner, unpublished data).
Assuming that the plasma concentration of corticosterone is an
indicator of the level of physiological stress, neither territorial
defense nor post-nuptial molt are stressful. We have, at this time,
no explanation for the elevated levels during the time of the
second brood.
In birds of the year the plasma level of corticosterone was
relatively high at fledging, about half the ~aximum level attained
by adults during the course of the breeding season. By the time
that adult body weight was attained during the post-juvenal molt it
had declined to about one-third of the level at fledging. The level
of plasma irLH was low at fledging. At about the time of attainment
of adult weight there was a transiant three-fold increase, the
significance of which is unclear.
Experience with our field system indicates that it is now feasible
to perform field experiments involving such manipulations as
implants of hormones, addition or removal of eggs from clutches,
and removal of competing territorial males, and to correlate
endocrine and behavioral changes induced thereby.
Proc. First lnternatl. Symp. Avian Endocrinology, Calcutta, Jan.
1977
15
BANERJEE, SEliMA
Endocrinology Laboratory, Department of Zoology, University of
Kalyani, Kalyani, India.
This report is concerned with the gross comparative anatomy and
cytomorphology of the thymus in male juvenile and adult Indian
birds: namely, fowl (Gallus domesticus), duck (Anas poecilorhyncha,
Foster), common pigeon {Columba livia, Gmelin), parrot (Psittacula
krameri), common myna (Acridotheres tristis, Linnaeus), house
sparrow (Passer domesticus, Linn,), crow (Corvus splendens,
Viellot) and red-vented bulbul (?ycnonotus cafer, Linn.). The
thymus is a paired organ. Each half consists of 8-11 separate lobes
occurring in the form of a chain on either side in the cer vical
region.
The cytomorphology of the thymus in all eight avian species reveals
a striking uniformity. In .juvenile birds the thymus is well de
veloped. Lobes are divided into lobules ~xcept in the duck and
sparrow). The lobular cortex is fairly extensive and exhibits a
high population density of thymocytes, along with a relatively
smaller number of medium and large lymphncytes, plasma cells and
reticular cells. The medullary region is characterized by a low
population of thymocytes and the frequent occurrence of blood
sinusoids, lymph channels and islands or cords of nonlymphocytic
c:ells. Besides typical mature reticular cells, six other cell
types have been histologically distinguished in the medulla. They
exist in the free state or as cellular elements of the cord.
Morphologically, some of these types disclose their identity as
degenerated and phagocytic reticulocytes, while others reveal the
presence of intracellular masses of <J.cidophilic and
PAS-positive material. In juvenile species Ha.ssall 1 s corpuscles
of thymus are formed from two to three layers of lanceolated cells
with a small c0re of central amorphous material.
In adult birds, there is a remarkable regression in the size of the
thymus lobes. Notable anatomical and cytomorphological changes
encountered in the involuted thymus are: (1) absence of lobulation
(except in the parrot and crow), (2) loss of corticomedullary de
marcation, (3) sharp fall in the population density of small
lympho cytes in the cortical region, (4) increase in the size and
number of non-lymphocytic cell types, (5) frequent occurrence of
the epi thelial cell-cords in some cases (duck, parrot and
sparrow) towards the periphery and (6) enlargement and maturation
of Hassall's corpuscles by cellular stratification and accumulation
of material in the central core.
Cellular architecture of the thymus in birds and the pattern of the
cytomorphological changes during age-involution are grossly similar
to those of mammalian thymus.
I am grateful to Dr. S.P. Bhattacharyya of Zoology Department, K.U.
for his supervision.
Proc. First lnternatl. Symp. Avian fndocrinology, Calcutta, Jan.
1977
16
Effects of hypercalcaemia on the ultimobranchial gland of pigeon,
Columba livia
* ** DAS, V.K. AND DAS, SOBHA
* Department of Zoology, Kamla Nehru Institute of Science &
Technology, Sultanpur, India, ** Department of Zoology, University
of Gorakhpur, Gorakhpur, India.
The present investigation deals with histophysiological observa
tions on ultimobranchial glands (UBG) of pigeons in relation to
plasma calcium. The experimental birds were subjected to hyp(:r
calcaemia by alternate daily intramuscular injections of vitamin D2
(25000 IU) and by providing them 1% CaC12 solution for drinking.
After 2, 6, 10, 15, 20 and 30 days of such treatment the serum
calcium rose relative to that in the controls.
The UBG of the control birds exhibits two main features: (i) the
glandular parenchyma consists of clustars of epithelial cells
embedded in connective tissue stroma, (ii) there are duct-like
follicles containing lHtle colloid and lined •,ti th a
single-layered cuboidal epithelium, Hypertrophy and hyperplasia of
the glandular parenchymatous cells have been noticed in
hypercalcaemic birds. Mitotic figures have also been encountered
after 10 days of treat ment. Hypertrophied calls lose their
staining capacity, perhaps due to removal of their secretory
product. After 25 days treat ment the UBG cells show degenerative
changes indicating that they become exhausted after continous
hyperactivity. No appreciable change was recorded in the follicles
and their luminal content.
These results suggest that hypercalcaemia induces the UBG to
secrete larger quanti ties of its prodnct (calcitonin) to counter
act experimental hypercalcaemia.
Proc. First lnternatl. Symp. Avian Endocrinology, Calcutta, Jan.
1977
17
OKSCHE,A.
Department of Anatomy and Cytobiology, Justus Liebig University of
Giessen, Giessen, Federal Republic of Germany
Phylogenetically, the avian hypothalamo-hypophysial system
has
attained a very high degree of morphological differentiation
and
functional specialization, by no means inferior to that observed
1n
mammals. From extensive neurohistological investigations
(Oksche,A.,
Farner,D.S., Adv.Anat.48/4, 1-136,1974; see also references), it
was
concluded that the hypophysiotropic nuclei of birds consist
of
cluster-like aggregations of differing neuroendocrine elements.
In
further studies our concept of anatomical subunits was extended
to
the parvocellular and magnocellular nuclei of the anterior
hypothala
mus. In birds, numerous parvo- and magnocellular perikarya
producing
different types of elementary granules were observed outside
the
hypophysiotropic zone of the tuber and the classical
neurosecretory
nuclei of the rostral hypothalamus. Not all of the secretory
parvo
and magnocellular neurons are connpcted to one of the
neurohemal
areas. Apparently, the avian hypothalamus produces not only
hypo
physiotropic and posterior lobe hormones but also other, to
date
only partly identified, peptides with a wide range of
biological
properties.
In an attempt to elucidate the intrinsic organization of
hypo
thalamic cell clusters, our most recent studies in Passer
domesticus
were concentrated on the periventricular aggregations of nerve
cells
at the level of the suprachiasmatic nucleus. According to
micro
fluorimetric analyses by H.G.Hartwig, this phylogenetically
archaic
region is unusually rich in noradrenergic afferents (see
Oksche,A.,
Gen.Comp.Endocrinol. 29,225, 1976). Not all of the secretory
peri
karya are separated by thin glial lamellae. The areas of
direct
somata-somatic apposition show specialized junctional zones
which
may play a role in cellular communication and electrotonic
coupling.
In addition, axon terminals containing vesicles can be
occasionally
situated between two neuronal somata. Perikarya containing
secretory
granules approximately 100 nm, ISO nm and 180 nm in diameter can
be
found in close proximity to the third ventricle. The
larger-sized
granules are produced in very conspicuous neurons which
topographi-
Proc. First lnternatl. Symp. Avian Endocrinology, Calcutta, Jan.
1977
18 cally correspond to the scattered aldehyde-fuchsin stainable
elements
of this region. Immunocytochemically, these cells appear to
contain
arginine vasotocin. All types of periventricular secretory
neurons
are embedded in a neuropil unusually rich in axodendritic
synapses
of different types and different degrees of complexity. In
contrast,
axosomatic synapses are relatively rare in the avian
hypothalamus.
The neuronal perikarya and the afferents of the avian
hypothalamus
are arranged in a patterned manner. The cluster-like subunits of
the
avian hypothalamic nuclei consist not only of cells
elaborating
different types of neurohormones and transmitter-like substances,
but
also of steroid-binding neurons, interneurons, intrinsic
collaterals
and afferents of differing origin, including ascending
aminergic
elements. Specialized zones of neuropil located between cell
clusters
and displaying numerous synapses may be essential for the
propagation
of excitation along certain channels and circuits. Specific
patterns
of intrahypothalamic synapses may be regarded as the anatomical
basis
for functional isolation or interaction, convergence or
divergence,
and integration of external and internal information. This
neuro
anatomical interpretation appears to be con3istent with
modern
functional concepts of neuronal networks. In the hypothalamus,
this
type of neuronal arrangement could explain the isolated
co-existence
of various functional systems within very circumscribed areas
and
also some spectacular signs of functional interaction. The
newly
acquired anatomical concepts will also aid in promoting
discussion
on the hypothalamic components of 'circadian oscillators' or
'bio
logical clocks' and on the character of the 'deep hypothalamic
photo
receptors'. It should be kept in mind that circadian oscillators
and
neuroendocrine effectors may be located in different
hypothalamic
areas. This spatial arrangement would require a complex
wiring
diagram including longitudinal fiber connections. Using a wide
spec
trum of combined electrophysiological and neurohistological
tech
niques, reciprocal connections have been demonstrated between
the
rostral and tuberal regions of the mammalian hypothalamus.
Exact
anatomical data in the avian system are urgently required.
In birds, the hypothalamic projections to the median eminence
are
characterized by tuberoinfundibular and anterior hypothalamic
path
ways. The latter consist of 'Gomori-negative' and
'Gomori-positive'
Proc. First lnternoti. Symp. Avian Endocrinology, Calcutta, Jon.
1977
19
component of the palisade layer in the anterior median
eminence.
Immunohistochemistry has opened up new prospects for the
selective
identification and mapping of secretory neurons producing
protein
neurohormones. Recently, BHihser (unpublished) has
surcessfully
visualized the arginine vasotocin-containing neurons of the
Zebra
Finch (PAP-method). Immunoreactive perikarya appear in all
subdivi-
s1ons of the magnocellular nuclei displaying aldehyde-fuchsin
stain-
able material, In addition to the main neurosecretory pathway,
the
external zone of the median eminence and the neural lobe are rich
in
heavily stained reaction produ,·t. There is an increasing body
of
electron microscopic evidence indicating that thP
'Gomori-positive'
elementary granules of the palisade layer are considerably
smaller
in diameter than those of the neural lobe: 130-150 nm versus
200-
250 nm. In analogy to mammals this mate rial may be closely
rorrelated
to the CRF. In an Attempt to complete the analysis,LHRH antibody
was
administered to hypothalamic sections of the Japanese
quail.Innnuno-
rf-""aetive ;~xn:l81 rer~.-·in.:-'ls ~·.t~=>rp nb3Prv;·d in
t~lt' p:::~lisn.::ir· 1: yPr r,r th0
anterior and posterior divisions of the medicm
eminence.Unfortunate- ------ ly, to date all investigators have
failed to map irmnunocytochemiral-
ly the LHRH-producing perikarya in the avian hypothalamus. An
immunocytochemiral proof of the TRH-system in birds is
lacking.
As birds phylogenetically descended from archosaurian reptiles
and
mammals from mammal-like reptiles, the r<"ptilian brain prnvidPs
the>
key for the comparison of avian and mammalian hypothalami. From
ex
tensive neuroanatomical studies wirh chelonian, crocodilian.
lac~r
tilian and ophidian species we were able to conclude that very
pr0-
nnunced di ffprPnt·es exist between these main systematic
groups
(Oksche,A.,Gen.Comp.Endocrinol.29, 225, 1976; Prasada Rdo,P.D. et
a!.,
Cell Tiss.Res._]_?Q, 63, 1976). The evolution of the
hypothalamus
depends greatly on the rearrangement of the structural
relationships
of the basic neuroendocrine units which already existed in
primirive
nervous systems (Lentz). The proliferation of cPll clusters
and
differentiation of specific synaptic patterns appear to hP
respons
ible for the increasing functional complexity ot the
hypnthCJlamus.
Proc. First lnternotl. Symp. Avian Endocrinology, Calcutta, Jon.
1977
20
FOLLETT, B.K.
Department of Zoology, University College of North Wales, Bangor,
Gwynedd, UK.
Since many of the recent advances in avian neuroendocrinology have
been published in the literature during the past three years it
might be useful to try and draw together this knowledge and see
whether a coherent model might be drawn therefrom. Let me first
list some of the various findings: 1. Long daylengths act by
stimulating increased LH and FSH secre tion. Radioimmunoassays are
now available to measure both avian LH and FSH and these have been
used to follow the changes in hor mone secretion under both
artificial photoperiods and natural day lengths. On transfer to
20L/4D LH and FSH concentrations rise rapidly (within one day - see
Follett & Davies, this volume) to reach peak values after 6-10
days. The 1H levels then remain relatively stable but FSH falls
away rapidly as the testes reach maturity (Follett, J. Endocrinol.
&2, 117, 1976). Thus, there is an asynchrony between 1H and FSH
secretion during the latter stages of gonadal maturation. Since the
metabolic clearance of 1H is identical under short days, long days
and in castrates it appears that the enhanced plasma levels are
indeed a result of increased pituitary secretion. 2. Gonadotrophin
secretion during the first couple of long days is rhythmic but this
soon disappears and secretion becomes con tinuous at all times of
day and night (Gledhill, B. & Follett, J. Endocrinol. ]1, 245,
1976). In other words, there is no evi dence for a diurnal rhythm
of secretion mirroring the circadian processes underlying
photoperiodic time-measurement. This not only applies to the quail
but also to the duck, the white crowned sparrow and the starling.
3. In contrast with mammals episodic secretion of LH and FSH is
less marked in quail. Gonadotrophin secretion - even of LH -
appears to be made up of a tonic component upon which is super
imposed some pulsatile hormone release. Long daylengths seem to act
primarily by increasing the tonic output rather than by altering
the amplitude/frequency of episodic secretion (c.f. sheep; Lincoln,
G.A. ~., J. Endocrinol. in press, 1977). 4. Once begun, LH &
FSH secretion may continue for anything up to a week without
further photostimulation. This so-called "carry-over" phenomenon
seems to be a characteristic property of the photoneuroendocrine
system. Since hypothalamic deafferen tation stops "carry-over"
& leads to an immediate fall in LH secretion it would appear to
be of hypothalamic origin. Put simply it appears that long days
cause a semi-permanent change in the neuroendocrine machinery and
elicit a prolonged period of enhanced gonadotrophin secretion. 5.
Sex steroid feedback. Sex steroids have a strongly negative
feedback action on LH and FSH secretion. Castration coupled with
long days leads to quite enormous increases in hormone levels which
often reach many hundred fold that seen in intact animals.
Proc. First lnternatl. Symp. Avian Endocrinology, Calcutta, Jan.
1977
21
Normally, therefore, ovarian and testicular steroids greatly
attentuate the photoperiodic response. Indeed, small increases in
exogenously administered androgens easily override the effect of
long days. Feedback resides at the level of both the pituitary and
the hypothalamus.
During the photoinduced sexual cycle there are some changes in
hypothalamic sex steroid sensitivity (e.g. Davies, D.T. et al.,
Gen. comp. Endocrinol. JQ, 477, 1976) but it seems certain (c.f.
sheep) that long days do not act by simply altering the sensitivity
of some "gonadostat" in the hypothalamus. This is shown by the fact
that gonadectomized quail are completely photoperiodic (Gibson, W.
et al., J. Endocrinol. ~. 87, 1975).
Davies, D.T. & Bicknell, R.J. (Gen. comp. Endocrinol. JQ, 487,
1976) have shown that the responsiveness of the quail's pituitary
to LH-RF increases slightly during the early phases of testicular
growth. It would seem, therefore, that this change, together with
that in sex steroid sensitivity, may serve to amplify the
pituitary's response to LH-RF but they are not the primary cause of
increased gonadotrophin secretion. Enhanced LH-RF secretion from
the median eminence under long days is extremely probable.
6. Within the hypothalamus are a number of discrete areas essential
for the photoperiodic response. Lesions in either the ventral or
dorsal regions of the infundibular nuclear complex ( posterior
hypothalamus) totally block the capacity of the quail to grow its
gonads under long daylengths. More recently, it has become clear
that areas in the anterior hypothalamus are also involved. Lesions
in the pre-optic region also block photoinduced testicular and
ovarian growth (see Davies & Follett, Proc. Roy. Soc. B, J21,
285 & 303, 1975). The converse experiments of stimulating the
hypothalamus with small electrical currents and then measuring
changes in LH secretion confirm the importance of the infundibular
nucleus and of the pre-optic region (Davies & Follett, J.
Endocrinol. £1, 431, 1975).
The obvious question then arises as play in the photoperiodic
response. to speculate that they are involved four functions:
to what functions these areas It seems not unreasonable
in one or more of the following
(a) The biological clock. Birds measure daylength using a cir
cadian clock but the location of this time-measuring device remains
unknown. Menaker and his colleagues have demonstrated that the
pineal may be one clock in the bird (see Gwinner, E., this volume)
but the removal of this organ seems to have little effect upon
photoinduced gonadal growth in most bird species so far tested
(although see Saxena, R.N., this volume). In rodents there is now
strong evidence that a clock, or at least an essential com ponent
of the clock, resides in the anterior hypothalamus and it is
tempting to wonder if the lesions in the pre-optic region of the
quail block testicular development by interfer ing with the bird's
daylength-measuring system. Recently, we (Davies and Jimpson, S.M.)
have found that preoptic lesions do interfere with some
clock-driven functions in the quail but the matter is still
Proc. First lnternatl. Symp. Avian Endocrinology, Calcutta, Jan.
1977
22
far from resolved.
(b) Location of the LH-RF producing cell bodies. The resolution of
this problem seems important since their location in either the
infundibular nucleus and/or the pre-optic region would clearly
reduce the number of potential neuroendocrine models. Un
fortunately, while it has proved possible to demonstrate LH-RF
nerve terminals in the median eminence by histochemical methods
(see Oksche, this volume) no-one has yet visualised the cell
bodies. Evidence from experiments where pituitary implants have
been placed in the quail's hypothalamus (Sharp, P.J., J.
Endocrinol. 5}, 329, 1973),or where LH-RF activity has been
measured following various hypothalamic lesions,have given
equivocal results, sugges ting that LH-RF might be manufactured
both in the anterior and posterior hypothalamus.
(c) There is good evidence that adrenergic nervous pathways are
somehow involved in photoperiodism. Intraventricular 6-0H dopamine
can block testicular growth (e.g. Davies & Follett, J.
Endocrinol. 60, 277, 1974) while reserpine stops the photoinduced
LH rise (Follett et al., J. Endocrinol, in press, 1977).
(d) The photoreceptor. There is unequivocal evidence (Benoit, J., p
121 in "La Photoregulation de la Reproduction chez les Oiseaux et
les Mammiferes", CNRS, 1970; Menaker, M. Biol. Reprodn • .!!, 295,
1971) that an extraretinal receptor exists in birds. Recently,
Bayle et al. (C.R. Acad. Sci.~. 1501, 1975) appear to have located
the receptor in the infundibular nuclear region of the quail's
hypothalamus - a finding which would accord well with our lesioning
findings. Possibly then, one function of the posterior hypothalamus
is as the photoreceptor for the photoperiodic response (but see
also Homma, K. and Sakakibara, Y., this volume).
It may still be premature to speculate how these various components
might be linked together into a system which regulates the photo
neuroendocrine response in birds. However, one does wonder if the
"clock" might not turn out to be some type of pulse generator whose
output is circadian. The photoreceptor could act as a gating
mechanism such that if the generator fired during lights-on then
signals might pass into the circuits regulating LH-RF sec retion.
At this point I suspect that this daily rhythmic input (under long
days) must somehow be converted into a continuous output in order
to allow for the sustained and continuous release of the
gonadotrophins. Whatever circuit might be involved at this stage
may have the property of remaining switched on for a number of
days, even in the absence of further input, thus ex plaining the
carry-over phenomenon. These ideas might well be totally incorrect
but if they serve as a stimulus for further experiments then
perhaps they are worth making!
Proc. First lnternatl. Symp. Avian Endocrinology, Calcutta, Jan.
1977
23
DOMINIC, C.J.
Department of Zoology, Banaras Hindu University, Varanasi,
India.
The hypophysial vascularisation in birds is reviewed with special
reference to the hypothalamo-hypophysial portal vessels. The median
eminence and the neural lobe are supplied by the infundi bular
artery which originates from the anterior ramus. The median
eminence is covered by a dense capillary plexus that is supplied by
the branches of the infundibular arteries. The capillaries that
form the plexus are generally distributed only on the outer surface
of the median eminence and do not penetrate the palisade layer.
Occasionally, capillaries from the primary plexus pene trate
deeply into the hypothalamus. The primary capillary plexus is
usually covered by the cells of the pars tuberalis. The primary
capillary plexus in the median eminence is either single or is
sometimes divided into an anterior and a posterior plexus. When the
plexus is divided, the two divisions are more or less
interconnected. However, in the White-crowned sparrow (Vitums, A.,
Mikami, S., Oksche, A. and Farner, D.S., Z. Zellforsch. ~. 541,
1964) and the Japanese quail (Sharp, P.J. and Follett, B.K., J.
Anat. lQ.!!, 227, 1969) the two divisions of the primary capillary
plexus do not appear to have any interconnections. The posterior
plexus is smaller than the anterior one and usually reaches up to
the ventral border of the infundibular stem. Irrespective of
whether the primary capillary plexus is single or divided, in al
most all species of birds investigated, there are separate anterior
and posterior groups of portal vessels. The anterior and posterior
groups of vessels originate from the anterior and posterior plexus,
or from the anterior and posterior regions of the undivided
capillary plexus. The anterior group of portal vessels traverses
the anterior margin of the porto-tuberal zone and breaks up into
capillaries in the sinusoids of the cephalic lobe of the pars
distalis. Likewise, the posterior group of portal vessels traverses
the posterior margin of the porto-tuberal zone and breaks up into
capillaries in the sinusoids of the caudal lobe. Each group of
portal vessels is formed from a few major vessels and several minor
vessels. There are no important interconnections between the two
groups of portal vessels. In some species the two groups of portal
vessels converge below the median eminence before entering the pars
distalis over a rela tively restricted area. However, in others
individual portal vessels may pass directly into the pars distalis
from the broad capillary plexus. In certain species additional
caudal portal vessels which do not belong to the posterior group of
portal vessels occur, These "accessory" portal vessels pass from
the infundibular stem to the pars distalis without traversing the
porto-tuberal zone and supply blood only to a circumscribed region
in the caudal lobe.
The incidence of distinct anterior and posterior groups of hypo
physial portal vessels was first convincingly demonstrated in
the
Proc. First lnternatl. Symp. Avian Endocrinology, Calcutta, Jan.
1977
24
White-crowned sparrow (Vitums et al., 1964). C.J. Dominic and R.M.
Singh (Gen. Comp. Endocrinol. 11, 22, 1969; J. Endocrinol. .!£l.,
3.5.5, 1971) and K.B. Singh and Dominic (Arch. Anat. micr. Morph.
exper. ~. 3.59, 197.5) demonstrated the existence of distinct
anterior and posterior groups of portal vessels in eighty four
species of birds belonging to several orders and thus emphasised
the generality of this phenomenon. A similar demonstration of the
separation of portal vessels into anterior and posterior groups in
the Japanese quail (Sharp, P.J. and Follett, B.K., J. Anat. 1Qk,
227, 1969) and in a number of other avian species (Assenmacher, I.,
Arch. Anat. micr. Morph. exper. hl_, 69, 1952; Duvernoy, H.,
Gainet, F. and Koritke, J.G., J. Neuro-Visc. Rel. ]1, 109, 1969)
again emphasises the widespread occurrence of the regional distri
bution of portal vessels in the avian pituitary.
It has been suggested that the existence of two separate groups of
portal vessels in the avian pituitary may be correlated with the
histological bipartition of the median eminence and of the pars
distalis, and provides morphological evidence for the existence of
two separate hypothalamic mechanisms regulating the secretory
activity of the avian pars distalis. Light microscopic studies show
that the anterior median eminence is rich in Gomori-positive fibres
of the supraoptico-paraventricular tract, whereas the posterior
median eminence is mostly composed of Gomori-negative fibres of the
tubero-infundibular tract (Oksche, A., Mem. Soc. Endocrinol. 12,
199, 1962). It is well established that the avian pars distalis-is
divided into cytologically distinct cephalic and caudal lobes
(Wingstrand, K.G., The Structure and Development of the Avian
Pituitary, C.W.K. Gleerup, Lund, 1951) and there exists a
functional differentiation between the two lobes. Hence, it appears
that the secretory activity of the cephalic lobe cells is regulated
primarily by the neuro-hormones from the supraoptic and
paraventricular nuclei travelling via the anterior group of portal
vessels, and that of the caudal lobe cells primarily by neuro
hormones from the tuberal nuclei travelling via the posterior group
of portal vessels. Even though on morphological grounds there is a
great attraction in the regional distribution of the portal vessels
having physiological significance, the experimental in
vestigations carried out to date (cf Stetson, M.H., Z. Zellforsch.
21, 369, 1969; ibid, 1JQ, 389, 1972; Sharp, P.J. and Follett, B.K.,
Neuroendocrinology, 2, 205, 1969) do not yet support the
idea.
Proc. First lnternatl. Symp. Avian Endocrinology, Calcutta, Jan.
1977
25
Potential sites and action spectra for encephalic photoreception in
the Japanese quail
KAZUTAKA HOMMA, YOSHIKAZU SAKAKIBARA AND MITSUAKI OHTA
Department of Veterinary Physiology, Faculty of Agriculture,
University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, Japan
113.
This paper considers the important role of encephalic photo
reception in the photo-gonadal reflex of the Japanese quail.
Preliminary work on this subject has been reported in Biochrono
metry (M. Menaker ed., 333-341, NAS Pub., 1971).
Sites of encephalic photoreception: Sites of encephalic photore
ceptionforthe photo-gonadal reflex were extensively examined by
chronically implanting small beads of radioluminoue paints for 21
days into various regions of the brain of young Japanese quail
reared under environmental 8:16 LD cycles. Some beads were de
signed eo as to illuminate one side only. Localized illumination by
this means in any one of the following locations brought about
unequivocal gonadal growth; 1) an extra-hypothalamic area facing
towards the mid-sagittal plane, 1 mm above the anterior commissure,
2) the anterior and the posterior hypothalamus, and J) small areas
of the midbrain, 2 mm lateral to the midsagittal plane on each side
and adjacent to the tractus occipitio-mescencephalicue. Illumi
nation in other locations of the brain gave no reproducible results
or any positive responses. Correlations between the effective sites
and the rate of gonadal growth supports the view that en cephalic
photosensitive neural structures for gonadal stimulation are
distributed within or close to the basal hypothalamus.
Action spectra and circadian rh.vthms: The action spectra of the
photoperiodic response as well as cyclic changes in encephalic
photosensitivity were investigated by employing light emitting
diodes (LED). Birds for these experiments had various LEDs sur
gically secured on to the skull (Figure). They were then sub
jected to continuous encephalic lighting for 14 days. The results
showed (Figure) that in the visible spectrum range, red light was
most stimulatory. Infrared light (949 nm) was neither stimulatory
nor inhibitory at the energy levels tested.
Using these data, night interruption experiments were carried out
with red LEDs (.535 nm). Different photoperiods were allotted to
groups of birds housed in the same chamber and lit with 8: 16 LD
cycles. Plasma testosterone and LH levels were markedly elevated
within 3 days in the group which received LED lights during the
second quarter of the 16 hr environmental dark period. The photo
periodic inducible phase assessed with LED lighting either by the
rate of gonadal growth, or by hormone levels agreed well with that
obtained by manipulating the on-off time of the room lights. It was
concluded that the effectiveness of direct light stimulation to the
brain is under the control of circadian mechanism and that the
light intensity necessary to induce maximum gonadal growth was far
below that needed for entrainment.
Proc. First lnternatl. Symp. Avian Endocrinology, Calcutta, Jan.
1977
:1.~ lJ 1a !14 ,......,..__
~ ~} UH\~ e"" ~ -eee
0 - "-:'1!~ .. ·~ ..... ::!. ~ ·~
~ 1!~~~ .~)
~-- -~ i ~ ~] ~ ..
"' ! .-s ~ 5 -r:!·' ~ ~ • ; 1! . • ~~ -~ -~ :i~~l - .;3·~ ~ ~ ~ ..
~~, .. ~-- .. - I 0 ·.:ll~
0 0 0 ~
Proc. First lnternatl. Symp. Avian Endocrinology, Calcutta, Jan.
1977
27
Effect of hydrocortisone on the hypertonic saline-induced changes
in the hypothalamic neurosecretory system of the spotted owlet,
Athene brama, Temminck
* SINGH, K.B.
Department of Zoology, Banaraa Hindu University, Varanaai 221005,
India •
Administration of a J% NaCl solution (1 ml/day) for 3 to 5 days
induced characteristic histological changes in the hypothalamic
neurosecretory system (HNS) of the spotted owlet. These changes
included a reduction in the quantity of neurosecretory material
(NSM) in all parts of the HNS, viz., the supraoptic nucleus (SON),
the paraventricular nucleus (PVN), the hypothalamo-hypophyaial
tract (TR) and the neural lobe (NL), as well as in a hypertrophy of
the neurosecretory neurons in the SON and PVN. During the initial
period (up to the third day) of hypertonic saline adminis tration,
the quantity of NSM in the zona externa of the median eminence (ME)
remained unchanged. However, when the treatment was continued
beyond 3 days, there was a marked reduction in the quantity of NSM
in the ME. The histological changes that occurred in the HNS
following hypertonic saline administration were completel~ blocked
by concurrent treatment with hydrocortisone (Efcorlin, BDH) (6
mg/animal/day).
Even tholl8h it is known that the histologically demonstrable NSM
is not the ADH (arginine vasotocin in birds) the close functional
relationship between the two is indicated by the depletion of both
from the HNS following water deprivation or NaCl adminis tration.
Hence, the hypertonic saline-induced histological changes in the
HNS are presumably indicative of augmented sec retion of ADH (see
Farner, D.S., Wilson, F.E. and Okache, A., In: Neuroendocrinology,
Vol. II, eda. 1. Martini and W.F. Ganong, Academic Preas, New York,
pp 529-582, 1967). The inhibition by hydrocortisone of these
changes in the spotted owlet is therefore suggestive of an
inhibition of ADH secretion. The mechanism of hydrocortisone
inhibition of anti-diuresis, however, is not clearly
understood.
* Present Address: Department of Zoology, Kamla Nehru Institute of
Science and Technology, Sultanpur-228oo1, India.
Proc. First lnternatl. Symp. Avian Endocrinology, Calcutta, Jan.
1977
28
Role of the pineal in the control of circadian and cir cannual
rhythms in European Starlings
GWINNER, E. Max-Planck-Institut flir VerhaltensphY-siologie, D-8131
Erling-Andechs, Germany
Within the last years it has become clear that the pineal organ
plays an important role in the control of biologi cal rhythms in
higher vertebrates. In mammals the pineal has been shown to be
involved in the regulation of annual rhythms, but for birds, it
appears that primarily daily rhythms are under pineal control.
Menaker and his cowor kers have found that pinealectomy has no
profound effects on the circadian rhythms of locomotor activity and
other functions of house sparrows as long as they were kept in
24-hour light-dark (LD) cycles. However, when pineal ectomized
birds were kept in constant darkness (DD) , these rhythms
disappeared. Implantation of pineals into the anterior chamber of
the eye restored the rhythms. On the basis of these and other
results Menaker proposed that the sparrow's pineal was the seat of
a circadian master oscillator. Its removal resulted in the loss of
selfsustainment in the circadian system and, hence, dampened the
overt circadian rhythms when no external Zeitgebers were present. -
Photoperiodic reactions were not impaired by pinealectomy (e.g.,
Menaker, M. and Zimmerman, N., Amer. Zool. 16, 45 (1976)-
Our own investigations on starlings have revealed that as in the
sparrow pinealectomy resulted in drastic dis turbances of the
circadian locomotor activity rhythms in birds kept in DD or in
constant light (LL). However, in contrast with the sparrow results,
pinealectomy in the starling did not usually lead to complete and
permanent arrhythmicity. In several cases arrhythmicity was only
temporary and many pinealectomized birds remained rhyth mic
throughout the 3 to 20 week experiments. The circa dian rhythms of
those birds that remained rhythmic, were altered in at least one of
the following aspects: (1) the circadian period was shortened, (2)
the circadian period was subject to sudden and apparently
spontaneous changes or (3) the separation between activity and rest
periods was less clear and the time of activity onset became more
variable. - Pinealectomy in the starling then leads to a general
loss of stability in the circa dian system but does not
necessarily abolish all self sustained circadian rhythmicity. The
results are con sistent with the assumption that the pineal organ
is a circadian master clock; however, the pineal does not seem to
be the only selfsustaining circadian oscillator involved in the
control of locomotor activity rhythms in that species.
Proc. First lnternotl. Symp. Avian Endocrinology, Ccl.:ul:·n, Jon.
1977
29
Since in the starling, as in other bird species, a cir cadian
rhythmicity is involved in photoperiodic time measurement it was of
interest to examine whether pineal ectomy would interfere with
photoperiodic reactions. In three types of experiments the
testicular reactions of pinealectomized, sham-operated and
unoperated birds were investigated: (1) birds were exposed to
sinusoidal chan ges of photoperiod, simulating the natural ones,
but with periods of only 6, 4 and 3 months, (2) photosen sitive
birds were exposed in midwinter to stimulatory long days or (3) to
continuous light. In none of these experiments did the
pinealectomized birds differ in any clear and consistent way from
the respecitve controls. The fact that this was true for the birds
exposed to LL is consistent with the proposition that a circadian
rhythmicity persists in pinealectomized birds even in the absence
of external Zeitgebers.
Proc. First lnternotl. Symp. Avian Endocrinology, Calcutta, Jon.
1977
30
SAXENA, R.N.
Department of Zoology, University of Delhi, Delhi, India.
There is no unanimity of opinion regarding the role of the pineal
in avian reproduction. While some workers have failed to demon
strate any relationship between the pineal and reproduction, others
have assigned pro- or anti-gonadotropic functions. In the present
review an attempt was made to reconcile these seemingly diverse
observations on the basis of the work done in our laborator.y on
the male Indian weaver bird, Ploceus philippinus. This bird is a
seasonal breeder with a reproductive cycle which can be divided
into breeding (June to July), regressive (August to October),
nonbreeding (November to Februar.y) and progressive phases (March
to May). It is known that these birds are highly photo sensitive
but a refractor.y period typical of most other seasonally breeding
birds is absent.
During the breeding phase of the male bird hypothalamic LHRH and
plasma LH levels were high whereas pi tui tar.y LH was low. LH
concentrations were measured by radioimmunoassay. The reverse was
true for the nonbreeding phase. Exposure of the birds to long
photoperiods (18L-6D) or pinealecto~ in winter (nonbreeding phase)
caused precocious testicular recrudescence along with changes in
the other secondar.y sexual characters typical of the breeding
phase within eight to ten weeks of light treatment. Corresponding
changes in the hormone levels were also observed. A combination of
pinealecto~ and long photoperiods advanced the attainment of the
breeding state as compared to a single treatment, suggesting that
the effects of long photoperiod and pinealecto~ on testicular
growth are additive. Gonadal regression and the chara cteristic
changes in the hormonal levels were blocked in birds
pinealectomised during the breeding phase and observed through the
nonbreeding phase. Pinealecto~ of birds exposed to nonstimu latory
short photoperiods (9L-15D) also caused gonadal recrudes cence and
parallel changes in the hormonal levels but the response was late
as compared to the birds under natural or long days.
To compare the antireproductive properties of the gland during
different phases of reproductive cycle, injections of partially
purified extracts of the pineal,obtained from birds throughout the
year, were given to photostimulated birds, unilaterally ovariec
tomized mice and pregnant rats. The pineal extracts from non
breeding birds had maximal inhibitor.y effects on the breeding
characteristics and hormonal levels in birds and also significantly
inhibited compensatory ovarian hypertrophy in mice and pregnancy in
rats. Pineal extracts from breeding birds had no such effects. The
inhibitor.y effects of pineal extracts from birds in other phases
(progressive and regressive) were also tested but were not as
significant as those from the nonbreeding phase.
Proc. First lnternatl. Symp. Avian Endocrinology, Calcutta, Jan.
1977
31
In vitro incubations of partially purified extracts of pineal with
pituitar.y isolated cells from male rats revealed significant LH
releasing potency during the breeding phase as well as in the
pineal of photostimulated birds. No such activity was detected
during the nonbreeding phase or in the pineah of birds kept in
short photoperiods. Corresponding changes in LH-releasing potency
were also observed in birds transferred from long to short
photoperiods or vice ~·
On the basis o