KPBI 02 Lab.man.Ug(Reviisi01)

8/12/2019 KPBI 02 Lab.man.Ug(Reviisi01)

1/14

LABORATORY MANUAL

ON URO-GENITALIA

IN MEDICAL BIOLOGY

DEPARTEMENT

DEPARTEMENT OF MEDICAL BIOLOGY

FACULTY OF MEDICINE

PADJADJARAN UNIVERSITY

BANDUNG

2004

1


2/14

INTRODUCTION

This laboratory activity on uro-genitalia in Medical Biology Department include:

Early deel!"#e$% !& %'e (r!-)e$*%al +y+%e#, e+"e*ally (r*$ary

+y+%e#.

Microscopic observation on early development of the chick are used as model of

human, because it is impossible to get the embryological preparation of the human for

microscopic study. or the early development of the human embryo !e used slides.

The period of embryological development stages are measured in hours "chick

embryo#, and the numbers of somite or period of time in days and !eek "human

embryo#.

$ll activity is carried on one !eek.

%


3/14

DEVELOPMENT OF T/E URO-GENITAL SYSTEM

The urinary and reproductive systems are intimately associated in origin,

development and certain final relations. Both arise in mesoderm that initially take the

form of a common uro-genital ridge, located on each side of the median plane.

&ertebrates have made three distinct e'periments in the production of kidneys. The

earliest and simplest e'cretory organ !as the pronephros, functional today only in

(


4/14

cyclostomes and a fe! fishes. The pronephros, nevertheless, does serve as a provisional

kidney in larval fishes and amphibians, but it is replaced by the mesonephros!hich

remains as the permanent kidney of these animals. The embryos of reptiles, birds and

mammals develop first a rudimentary and functionless pronephros and then a

mesonephros "functional during a part of fetal life#, !hereas the final kidney is a ne!

organ, the metanephros.These three kidney overlappingly, one caudad of the other, in the

order indicated by their names.

DEVELOPMENT OF T/E MESONEP/RIC IDNEY AND GENITAL RIDGE

The pronephros is entirely functionless in higher vertebrates, the mesonephros serve

these embryos as a temporary e'cretory organ that overlaps the initial activity of

permanent kidney. )n most, but not all, mammals function is attained* even in man,

!hose mesonephros is not large, this is apparently true until the tenth !eek.

The mesonephros of each side, like the pronephros, consists of a series of tubule, each

of !hich at one end becomes associated !ith a knot of blood vessels and at the other end

opens into the e'cretory duct. Mesonephric tubules drain into the same e'cretory duct

that began its development in relation to the pronephros.

The adult form of the kidney, therefore, may be regarded as an opisthonephros,

composed of mesonephric and metanephric renal units. +ollecting ducts develop as

evaginations of the mesonphric duct and the renal unit discharge their contents into those

collecting ducts. +ollecting ducts consists of pro'imal renal tubules and distal renal

tubules. To complete a mesonephric tubule there is further canaliation, gro!th !ith -

shaped banding, and association !ith a glomerulus. The free end of the tubule enlarges


5/14

and becomes thin-!alled !hena kont of blood vessels "the glomerulus# indents one side.

The double-!alled cup, thus formed, is theglomerular"or Bo!man/s# capsule.

DEVELOPMENT OF T/E URO-GENITAL SYSTEM OF /UMAN EMBRYO

The primitive se' gland makes its appearance !ithin a localied region of the

thickening that has already been described as the uro-genital ridge* this folded ridge is

appropriately named since it contains both the nephric and and genital promordia.

0


6/14

n the ventromedial surface of the urogenital ridge the peritoneal epithelium begins

to thicken "2 mm, embryos# and rapidly becomes several layers thick. 3roliferation soon

causes this region to bulge into the coelom as the genital ridge. This thickened strip

e'tends longitudinally and thus parallels the mesonephric ridge, but lies medial to it. $t

si' !eeks, the longitudinal furro!s separate the indifferent se' gland from the

mesonephros laterally, and from the mesentery of the gut, medially.

DEVELOPMENT OF T/E PRONEP/ROS-MESONEP/ROS-METANEP/-

ROS OF T/E /UMAN EMBRYO

The human pronephros is vestigial, it is a !ell develop as that of other amniotes

embryos. )t consists of several pair of rudimentary pronephric 4tubules5, arising as

2


7/14

dorsolateral sprouts from the longitudinally fused nephrotomes "the nephrogenic cord# of

each side.

6ven preceding the appearance of tubule primordial at 17 somites, a cellular strand

has split a!ay from the corresponding cord. This hollo!s as the primitive excretory duct,

and the pronephric tubules 8oin the duct. The degeneration of pronephric tubules is

complete at about the 0 mm. stage, but the e'cretory duct persists.

The formation of mesonephric primordia commences at about somite 11 in human

embryos !ith some 19 somites. )n a mm. embryo the caudal limit is reached at the

t!enty-si' somite . 6mbryos four nine !eeks old have a rather constant number of about

(7 tubules in each mesonephros.


8/14

)n all, a ma'imum number of about 7 pairs of tubules is possible, of !hich some 1

pairs still persist at nine !eeks. ;alf of these are already non-functional, !hile !ithin

another !eek all becomes discontinuous* yet the ma'imum degeneration attained is not

complete until the end of the fourth month. The glomeruli occupy a median column* the

duct is lateral and the tubules are intermediate and dorsal in position.

The development of the metanephros:

The permanent kidney of amniotes "reptiles, birds and mammals# arises far caudad in

the body. $s in the case of the mesonephros, the final kidney consists of an aggregate of

tubules !hich into a common duct. $lso like the mesonephros, the metanephros is double

9


9/14

origin* but in this instance the boundary bet!een the t!o components lies mid!ay of the

uriniferous tubules themselves.

The mesonephric duct makes a sharp bend 8ust before 8oining the cloaca. )t is at this

angle "level of the t!enty-eight somite, or the future first sacral vertebra# that the so-

called ureteric bud soon arises.

The internal layer of the metanephrogenic tissue subdivides into a corresponding

number of masses. During the seventh !eek some of the nephrogenic tissue about the

ends of the collecting tubules condenses into spherical masses* these hang do!n in the

angles bet!een the end-buds of collecting tubules and their parent stems "ig.$#. ne


10/14

such metanephric sphere is the fore-runner of each secretory tubule. The formation of

ne! spheres and their transformation into tubules continue at progressively higher levels

as the corte' thickens and the stem tubules continue to branch. The stage of a solid sphere

is soon converted into a vesicle !ith an eccentrically placed cavity "ig. $,B#. The

17


11/14

vesicle then elongates, thereby producing an -shaped secretory tubule "ig.+# !hich

unites at one end !ith the ad8acent terminal collecting tubule"ig.D#. The thinner-!alled,

blind end of the tubule becomes the glomerular capsule "Bo!man/s# of a renal

corpuscle "ig.D,6#. The stage of the -shaped tubule is follo!ed by marked elongation

and t!isting "ig.,=#.

*d$ey+

>hen a kidney is sliced length!ise, it is possible to see that the renal artery and vein

have many branches inside it "ig: 1a#. >ithout the presence of the blood vessels, it is

easier to identify three regions of a kidney. The renal corte' is an outer granulated layer

that dips do!n in bet!een a radially striated, or lined, inner layer called the renal

medulla. The renal medulla consists of cone-shaped tissue masses called renal pyramids.

The renal pelvis is a central space, or cavity, that is continuous !ith the ureter "ig:1b#.

Microscopically, the kidney is composed of over one million nephrons, sometime call

renal or kidney tubules "ig: 1c#. The nephrons produce urine and are positioned so that

the urine flo!s into a collecting duct. everal nephrons enter the same collecting duct*

the collecting ducts enter the renal pelvis.

11


12/14

F*)1

6ach nephron has its o!n blood supply, including t!o capillary regions. rom the

renal artery, an afferent arteriole leads to the glomerulus, a knot of capillaries inside the

glomerular capsule. Blood leaving the glomerulus enters the efferent arteriole and then

peritubular capillaries, !hich surround the rest of the nephron. rom there the blood goes

into a venule that 8oins the renal vein. The arro! in igure % sho! the path of blood about

a nephron.

1%


13/14

F*)1 2

C!$)e$*%al Cy+%* *d$ey

$ccording to the 4nonunion5 theory of the formation of renal cysts, the collecting

and e'cretory tubules fail to 8oin. The e'cretory units develop then in a normal manner

and may even form functional glomeruli. $ccumulation of urine in the convoluted

tubules, ho!ever, causes them to dilate and gradually to form cysts. More recent

1(


14/14

evidence suggests that the initial defect lies in the abnormal formation or function in the

pro'imal convoluted tubules. Degenerative changes then occur and multiple cysts form.

Re$al A)e$e+*+

Bilateral and unilateral renal agenesis is presumably caused by an early

degeneration of the ureteric bud. >hen the ureteric bud does not reach the metanephric

tissue cap, the latter fails to proliferate.

Pel* a$d /!r+e+'!e 3*d$ey

ometimes both kidneys are pushed so close together during their passage

through the arterial fork that the lo!er poles fuse. This results in the formation of a

horseshoe kidney "ig: (B#. The horseshoe kidney is usually located at the level of the

lo!er lumbar vertebrae, since its ascent is prevented by the root of the inferior mesenteric

artery "ig: (B#. The ureters arise from the anterior surface of the kidney and pass ventral

to the isthmus in a caudal direction.

F*)1

1

Documents

KPBI 02 Lab.man.Ug(Reviisi01)