Animal Science 434

Animal Science 434Animal Science 434

Lecture 11: The Luteal Phase of the Estrous Cycle

Lecture 11: The Luteal Phase of the Estrous Cycle

0

2

4

6

8

10

12

14

0 2 4 6 8 10 12 14 16 18 20 22

Day of the Estrous Cycle

Relative Progesterone Level (Blood)

Lu

teo

lysi

s

P4

Production(Diestrus)

P4

Production(Diestrus)

CLFormation(Metestrus)

Rel

ativ

e P

rog

este

ron

e L

evel

s (B

loo

d)

Fo

llicu

lar

Ph

ase

Luteal Phase

Ovulation Ovulation

• steroid synthesis– progesterone

• collagenase– theca interna

• present 1-3 days following ovulation

• blood vessels in follicle wall rupture

• walls collapse

• cells intermix

• old basement membrane becomes connective tissue of CL

• increases in size– papilla forms

• composed of cells from the granulosa and theca interna

• progesterone production increases

• a small cavity may be present where the folliclular antrum was present

Bovine Luteal Anatomy

Bovine Luteal Anatomy

Ovine Luteal Anatomy

Ovine Luteal Anatomy

Swine Luteal Anatomy

Equine Luteal Anatomy

Equine Luteal Anatomy

Luteal TissueLuteal Tissue

• Large cells from granulosa

• Small cells from the theca interna

• Large cells from granulosa

• Small cells from the theca interna

Mitochondria

SecretoryGranules

- Oxytocin- Relaxin

Functional Capability of CLFunctional Capability of CL• the number of luteal cells

– large cells undergo hypertrophy (3 fold)– small cells undergo hyperplasia (5 fold)

• vascularization of CL– Initiated by angiogenic factors from

follicle– Vascularity effects CL steroid synthesis

and delivery of hormones

• Insufficient CL function– Failure to maintain pregnancy– Important in domestic animals

• the number of luteal cells– large cells undergo hypertrophy (3 fold)– small cells undergo hyperplasia (5 fold)

• vascularization of CL– Initiated by angiogenic factors from

follicle– Vascularity effects CL steroid synthesis

and delivery of hormones

• Insufficient CL function– Failure to maintain pregnancy– Important in domestic animals

Progesterone Targets

Action of ProgesteroneAction of Progesterone

• reduces GnRH pulse amplitude and frequency

• prevents behavioral Estrus

• stops the preovulatory LH surge

• reduces mymetrial tone

• stimulates endometrial gland development and secretion

• stimulates aveolar development in mammary gland

• reduces GnRH pulse amplitude and frequency

• prevents behavioral Estrus

• stops the preovulatory LH surge

• reduces mymetrial tone

• stimulates endometrial gland development and secretion

• stimulates aveolar development in mammary gland

Progesterone Production by Luteal Cells

LuteolysisLuteolysis

• Uterus

• PGF2

• Oxytocin

• Uterus

• PGF2

• Oxytocin

Luteolysis in Cows,

Ewes, Sows


• Uterus

• PGF2

• Oxytocin

• Uterus

• PGF2

• Oxytocin

Prostaglandin F2Control of Luteolysis

Progesterone fromCL stimulatesproduction of uterine PGF2afterday 15 in cow

Uterine Horn

UterineVein

Prostaglandin synthesisby uterine endometriumis released into the uterine vein.

Oviduct

Ovary

CorpusLuteum

PGF2 is picked up by ovarian artery through counter current exchangeand delivered back to theovary where it causeslysis of the CL

Uterine ArteryUterine Artery

Ovarian Pedicle

PGF

PGF into Artery

Luteolysis in Mares

50% of CL’s maintained

CL regresses on day 17

%50 of CL’s maintained

CL maintained >30 days

Blood Supply to Uterus and Ovary in the Mare

PGF Not Effective (Cow, Ewe)PGF Not Effective (Cow, Ewe)

PGF Not Effective (Sow)PGF Not Effective (Sow)


• Uterus

• PGF2

• Oxytocin

• Uterus

• PGF2

• Oxytocin

Relationship of Oxytocin and PGF2

Uterus

Ovary

CL

PGF2

Anterior Pituitary

Posterior Pituitary

Oxytocin


• decreased blood flow

• cellular response– apoptosis– progesterone synthesis

• Immune response– Lymphocytes– Macrophages




ER

IP3

Ca++








Menstrual CycleMenstrual Cycle

FSHLHLH

EstradiolEstradiol

ProgesteroneProgesterone

FollicleOvulation

Corpus LuteumCorpus

Albicans

2 4 6 8 10 14 16 18 20 22 24 26 28 212

Anterior Pituitary

Hormones

Ovarian Hormones

Ovary

UterineEndo-

metrium

RecruitmentSelectionDominance

Recruitment

Luteolysis in the Primate

• Does not require the uterus

• CL lifespan in the human is 12-14 days unless pregnancy occurs– In the absence of pregnancy, CL self

destructs

FSHLHLH

EstradiolEstradiol


FollicleOvulation

Corpus Luteum

2 4 6 8 10 14 16 18 20 22 24 26 28 212

Anterior Pituitary

Hormones

Ovarian Hormones

Ovary

UterineEndo-

metrium

Men

ses

Men

ses

Men

ses

Men

ses

5days

5days

5 days

5 days

Fo

llicu

lar

Ph

ase

Fo

llicu

lar

Ph

ase

9 days9 days

Lu

teal

Ph

ase

Lu

teal

Ph

ase

14 days14 days

Variation in Menstrual Cycle Length

35-daycycle

Ovulation

14 days14 days

Menses Foll. Phase Luteal Phase Menses

28-daycycle Menses Luteal Phase MensesFoll. Phase

25-daycycle Menses Foll. Phase MensesLuteal Phase

14 days14 days

5 days5 days

5 days5 days

5 days5 days

6 days6 days

9 days9 days

16 days16 days 14 days14 days

BreastTenderness

BreastTenderness

Menstural Cycle Length

• AGELength

15 - 19 year olds 35 days 30 year olds 30 days 35 year olds 28 days

Variation More in teenagers Less in women in peak reproductive years

HypothalamusHypothalamus

GnRHGnRH

AnteriorPituitary

AnteriorPituitary

CL FollicleOvary

LH, FSH

LH LH, FSH

Inhibin (-)

EstradiolEstradiol (-)

(-)


HypothalamusHypothalamus

GnRHGnRH

AnteriorPituitary

AnteriorPituitary

FollicleOvary

LH, FSH

LH, FSH

Inhibin (-)

EstradiolEstradiol (+)

Est

rad

iol

pg

/ml

LH

m

IU/m

l FS

H m

IU/m

lP

rog

. ng

/ml

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Animal Science 434