1. Lecture 11: The Luteal Phase of the Estrous and Menstrual Cycle
Animal Science 434
Lecture 11: The Luteal Phase of the Estrous and Menstrual Cycle

2. Ovulation Ovulation Luteal Phase Follicular Phase P4 ProductionCL
Formation
(Metestrus)
Follicular Phase
Relative Progesterone Levels (Blood) P4
Production
(Diestrus)
Luteolysis

3. steroid synthesis
progesterone
collagenase
theca interna

4. present 1-3 days following ovulation
blood vessels in follicle wall rupture
walls collapse
cells intermix
old basement membrane becomes connective tissue of CL

5. 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

6. Luteal Tissue Large cells from granulosa
Small cells from the theca interna

8. Mitochondria
Secretory
Granules
- Oxytocin
- Relaxin

9. Functional 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

10. Progesterone Targets Blocks Estrus Negative Feedback
Aveolar Development

11. Progesterone Production by Luteal Cells

12. Luteolysis
Uterus
PGF2a
Oxytocin

13. Luteolysis in Cows, Ewes, Sows

14. Luteolysis
Uterus
PGF2a
Oxytocin

15. Prostaglandin F2a Control of Luteolysis
Uterine Horn
Progesterone from
CL stimulates
production of
uterine PGF2a after
day 15 in cow
Prostaglandin synthesis
by uterine endometrium
is released into the
uterine vein.
Corpus
Luteum
Oviduct
Ovary
Uterine
Vein
Ovarian Pedicle
PGF
PGF2a is picked up by
ovarian artery through
counter current exchange
and delivered back to the
ovary where it causes
lysis of the CL
PGF into Artery
Uterine Artery

16. Luteolysis in Mares CL regresses on day 17 CL maintained >30 days
%50 of CL’s maintained
50% of CL’s maintained

17. Blood Supply to Uterus and Ovary in the Mare

18. PGF Not Effective (Sow)
PGF Not Effective (Cow, Ewe, Mare)

19. Luteolysis
Uterus
PGF2a
Oxytocin

22. Relationship of Oxytocin and PGF2a
Posterior Pituitary
Anterior Pituitary
Oxytocin CL
PGF2a
Ovary
Uterus

23. Luteolysis decreased blood flow cellular response Immune response
apoptosis
progesterone synthesis
Immune response
Lymphocytes
Macrophages

24. IP3
Ca++ ER

25. Luteolysis decreased blood flow cellular response Immune response
apoptosis
progesterone synthesis
Immune response
Lymphocytes
Macrophages

26. Menstrual Cycle

27. Anterior Pituitary HormonesLH
FSH
Progesterone
Ovarian Hormones
Estradiol
Ovulation
Corpus
Albicans
Follicle
Corpus Luteum
Ovary
Recruitment
Recruitment
Dominance
Selection
Uterine
Endo-
metrium 2 4 6 8 10 12 14 16 18 20 22 24 26 28 2

28. Luteolysis in the Primate
Does not require the uterus
CL lifespan in the human is days unless pregnancy occurs
In the absence of pregnancy, CL self destructs
Possible intra-ovarian oxytocin receptors and PGF2a production
Menstruation
Drop in P4 and E2
Endometrial PGF2a, vasoconstriction, necrosis
Endometrial inflammation and tissue degeneration