Animal Science 434 Lecture 12: Spermatogenesis. Spermiation.
Animal Science 434
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Transcript of Animal Science 434
Animal Science 434
Lecture 11: The Luteal Phase of the Estrous and Menstrual Cycle
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Day of the Estrous Cycle
Relative Progesterone Level (Blood)
Lute
olys
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P4
Production(Diestrus)
CLFormation(Metestrus)
Rel
ativ
e Pr
oges
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ne L
evel
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lood
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Folli
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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
Luteal Tissue
• Large cells from granulosa
• Small cells from the theca interna
Mitochondria
SecretoryGranules
- Oxytocin- Relaxin
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
Progesterone TargetsAveolar
Development
Blocks EstrusNegative Feedback
Progesterone Production by Luteal Cells
Luteolysis
• Uterus• PGF2
• Oxytocin
Luteolysis in Cows,
Ewes, Sows
Luteolysis
• Uterus• PGF2
• Oxytocin
Prostaglandin F2Control of LuteolysisProgesterone 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 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, Mare)
PGF Not Effective (Sow)
Luteolysis
• Uterus• PGF2
• Oxytocin
Relationship of Oxytocin and PGF2
Uterus
Ovary
CL
PGF2
Anterior Pituitary
Posterior Pituitary
Oxytocin
Luteolysis
• decreased blood flow
• cellular response– apoptosis– progesterone synthesis
• Immune response– Lymphocytes– Macrophages
ER
IP3
Ca++
Luteolysis
• decreased blood flow
• cellular response– apoptosis– progesterone synthesis
• Immune response– Lymphocytes– Macrophages
Menstrual Cycle
FSHLH
Estradiol
Progesterone
FollicleOvulation
Corpus LuteumCorpus
Albicans
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Anterior Pituitary
Hormones
Ovarian Hormones
Ovary
UterineEndo-
metrium
RecruitmentSelection DominanceRecruitment
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– Possible intra-ovarian oxytocin receptors and PGF2
production• Menstruation
– Drop in P4 and E2
– Endometrial PGF2, vasoconstriction, necrosis– Endometrial inflammation and tissue degeneration