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Animal Science 434 Lecture 11: The Luteal Phase of the Estrous Cycle and the Menstrual Cycle in Primates
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Ovulation Ovulation Luteal Phase Follicular Phase P4 Production
CL Formation (Metestrus) Follicular Phase Relative Progesterone Levels (Blood) P4 Production (Diestrus) Luteolysis
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steroid synthesis progesterone collagenase theca interna
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present 1-3 days following ovulation
blood vessels in follicle wall rupture walls collapse cells intermix old basement membrane becomes connective tissue of CL
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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
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Luteal Tissue Large cells from granulosa
Small cells from the theca interna
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Mitochondria Secretory Granules - Oxytocin - Relaxin
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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
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Progesterone Targets Blocks Estrus Negative Feedback
Aveolar Development
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Progesterone Production by Luteal Cells
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Luteolysis Uterus PGF2a Oxytocin
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Luteolysis in Cows, Ewes, Sows
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Luteolysis Uterus PGF2a Oxytocin
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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
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Luteolysis in Mares CL regresses on day 17 CL maintained >30 days
%50 of CL’s maintained 50% of CL’s maintained
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Blood Supply to Uterus and Ovary in the Mare
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PGF Not Effective (Sow)
PGF Not Effective (Cow, Ewe, Mare)
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Luteolysis Uterus PGF2a Oxytocin
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Relationship of Oxytocin and PGF2a
Posterior Pituitary Anterior Pituitary Oxytocin CL PGF2a Ovary Uterus
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Luteolysis decreased blood flow cellular response Immune response
apoptosis progesterone synthesis Immune response Lymphocytes Macrophages
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IP3 Ca++ ER
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Luteolysis decreased blood flow cellular response Immune response
apoptosis progesterone synthesis Immune response Lymphocytes Macrophages
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Menstrual Cycle
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Anterior Pituitary Hormones
LH 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
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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
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Anterior Pituitary Hormones
Menses 5 days Follicular Phase 9 days Luteal Phase 14 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
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Variation in Menstrual Cycle Length
25-day cycle Menses Foll. Phase Luteal Phase 5 days 6 days 14 days 28-day cycle Menses Luteal Phase Foll. Phase 5 days 9 days 14 days 35-day cycle Menses Foll. Phase Luteal Phase 5 days 16 days 14 days Ovulation Breast Tenderness
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Menstural Cycle Length
AGE Length year olds days 30 year olds days 35 year olds days Variation More in teenagers Less in women in peak reproductive years
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Hypothalamus (-) Progesterone Estradiol (-) GnRH Anterior Pituitary Inhibin (-) LH, FSH LH, FSH LH CL Follicle Ovary
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Hypothalamus Estradiol (+) GnRH Anterior Pituitary Inhibin (-) LH, FSH LH, FSH Follicle Ovary
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LH mIU/ml FSH mIU/ml Estradiol pg/ml Prog. ng/ml
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