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Maternal Recognition of Pregnancy - Anatomy & Physiology (view source)
Revision as of 22:09, 13 September 2008
, 22:09, 13 September 2008no edit summary
* There must be at least two conceptuses in each uterine horn for pregnancy to be maintained.
* There must be at least two conceptuses in each uterine horn for pregnancy to be maintained.
* If they are not present in one uterine horn, PGF2α will be secreted in an endocrine fashion and luteolysis will occur, thus terminating the pregnancy.
* If they are not present in one uterine horn, PGF2α will be secreted in an endocrine fashion and luteolysis will occur, thus terminating the pregnancy.
== Mare ==
* The presence of a conceptus prevents luteolysis.
* In the presence of a conceptus, endometrial production of PGF2α is significantly reduced.
* The conceptus must migrate within the uterus from one uterine horn to the other 12-14 times a day during days 12, 13 and 14 of gestation in order to inhibit PGF2α.
* This migration is necessary, as the equine conceptus does not elongate, so there is less contact between the conceptus and the endometrial surface.
* It must move to distribute pregnancy recognition factors to the endometrial cells.
* The conceptus does produce proteins to effect the recognition of pregnancy, but specific roles are unknown.
* The luteolysin in the non-pregnanct cycle is thought to be PGF2α.
=== Conceptus ===
* The embryo takes 6 days to traverse the oviduct (in other species this is normally ~4 days). It stops at various spots in the uterus, spending 5-20 minutes in each.
* The conceptus remains spherical in shape.
* Day 6-22: the trophectoderm secretes a glycocalyx, which hardens to form a capsule.
** This prevents attachment of the embryo to the uterine endometrium.
* Day 7-17: Peristaltic contractions of the uterine myometrium move the embryo around the uterus.
** The conceptus begins to secrete oestrogens, but their role is unknown.
* Day 17: The myometrium clamps the embryo in position at the base of the uterine horns, preventing movement.
* If pregnant, upregulation of oxytocin receptors between day 10-16 is inhibited.