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Animal Science 434

Animal Science 434. Lecture 11: The Luteal Phase of the Estrous Cycle. Ovulation. Ovulation. Luteal Phase. CL Formation (Metestrus). Follicular Phase. P 4 Production (Diestrus). Relative Progesterone Levels (Blood). Luteolysis. steroid synthesis progesterone collagenase

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Animal Science 434

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

  2. Ovulation Ovulation Luteal Phase CL Formation (Metestrus) Follicular Phase P4 Production (Diestrus) Relative Progesterone Levels (Blood) 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. Bovine Luteal Anatomy

  7. Bovine Luteal Anatomy

  8. Ovine Luteal Anatomy

  9. Ovine Luteal Anatomy

  10. Swine Luteal Anatomy

  11. Equine Luteal Anatomy

  12. Equine Luteal Anatomy

  13. Luteal Tissue • Large cells from granulosa • Small cells from the theca interna

  14. Mitochondria Secretory Granules - Oxytocin - Relaxin

  15. 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

  16. Progesterone Targets

  17. Action 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

  18. Progesterone Production by Luteal Cells

  19. Luteolysis • Uterus • PGF2a • Oxytocin

  20. Luteolysis in Cows, Ewes, Sows

  21. Luteolysis • Uterus • PGF2a • Oxytocin

  22. Prostaglandin synthesis by uterine endometrium is released into the uterine vein. Prostaglandin F2a Control of Luteolysis Uterine Horn Progesterone from CL stimulates production of uterine PGF2a after day 15 in cow 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

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

  24. Blood Supply to Uterus and Ovary in the Mare

  25. PGF Not Effective (Sow) PGF Not Effective (Cow, Ewe)

  26. Luteolysis • Uterus • PGF2a • Oxytocin

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

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

  29. IP3 Ca++ ER

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

  31. Menstrual Cycle

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

  33. 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

  34. Menses Menses Luteal Phase Follicular Phase 5 days 5 days 14 days 9 days Anterior Pituitary Hormones LH FSH Progesterone Ovarian Hormones Estradiol Ovulation Follicle Corpus Luteum Ovary Uterine Endo- metrium 2 4 6 8 10 12 14 16 18 20 22 24 26 28 2

  35. 25-day cycle Menses Foll. Phase Luteal Phase Menses 28-day cycle Menses Foll. Phase Luteal Phase Menses Menses Foll. Phase Luteal Phase Menses Variation in Menstrual Cycle Length 5 days 6 days 14 days 5 days 9 days 14 days 35-day cycle 5 days 16 days 14 days Ovulation Breast Tenderness

  36. Menstural Cycle Length • AGE • Length • 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

  37. (-) Estradiol Progesterone (-) Inhibin (-) Hypothalamus GnRH Anterior Pituitary LH, FSH LH, FSH LH CL Follicle Ovary

  38. Inhibin (-) Hypothalamus (+) Estradiol GnRH Anterior Pituitary LH, FSH LH, FSH Follicle Ovary

  39. LH mIU/ml FSH mIU/ml Estradiol pg/ml Prog. ng/ml

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