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Corpus Luteum Regression - Anatomy & Physiology (view source)
Revision as of 21:25, 12 September 2008
, 21:25, 12 September 2008no edit summary
<big><center>[[Female_Reproductive_Tract_-The_Ovary_-_Anatomy_%26_Physiology#Processes_Taking_Place_In_The_Ovary|'''BACK TO PROCESSES TAKING PLACE IN THE OVARY''']]</center></big>
<big><center>[[Female_Reproductive_Tract_-The_Ovary_-_Anatomy_%26_Physiology#Processes_Taking_Place_In_The_Ovary|'''BACK TO PROCESSES TAKING PLACE IN THE OVARY''']]</center></big>
* Prostaglandin F2 (PGF2)
* Prostaglandin F2α (PGF2α)
* PGF2 from the uterus is transported to the ipsilateral ovary through a vascular counter-current exchange mechanism.
* PGF2α from the uterus is transported to the ipsilateral ovary through a vascular counter-current exchange mechanism.
* This involves two closely associated blood vessels in which blood from one vessel flows in the opposite direction to that of the adjacent vessel.
* This involves two closely associated blood vessels in which blood from one vessel flows in the opposite direction to that of the adjacent vessel.
* Low molecular weight substances in high concentrations in one vessel cross over into the adjacent vessel, where they are low in concentration.
* Low molecular weight substances in high concentrations in one vessel cross over into the adjacent vessel, where they are low in concentration.
* The ovarian artery lies in closs association with the utero-ovarian vein.
* The ovarian artery lies in closs association with the utero-ovarian vein.
* By counter-current exchange, PGF2 is transferred across the wall of the uterine vein into the ovarian artery by passive diffusion.
* By counter-current exchange, PGF2α is transferred across the wall of the uterine vein into the ovarian artery by passive diffusion.
* This ensures a high proportion of PGF2 produced by the uterine glands will be transported directly to the ovary and corpus luteum without dilution in the systemic circulation.
* This ensures a high proportion of PGF2α produced by the uterine glands will be transported directly to the ovary and corpus luteum without dilution in the systemic circulation.
* This is an important mechanism, because much PGF2 is denatured during one pass through the circulatory system. This is about a 90% loss in the ewe and cow.
* This is an important mechanism, because much PGF2α is denatured during one pass through the circulatory system. This is about a 90% loss in the ewe and cow.
== Luteolysis in Ruminants ==
* The ruminant corpus luteum secretes large amounts of oxytocin as well as progesterone.
* In the late luteal phase, oxytocin receptors develop on the uterine endometrium.
* Binding of oxytocin to the receptors stimulates the pulsatile release of PGF2α.
* PGF2α secretion by the endometrium is almost non-existant during the first half of the luteal phase.
* During the late luteal phase, pulses of PGF2α secretion increase in frequency and amplitude as the end of the luteal phase approaches.
* A critical number of