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Oestrous Cycle - Anatomy & Physiology (view source)
Revision as of 11:28, 11 September 2008
, 11:28, 11 September 2008→Cyclic Changes in the Ovaries
* As the corpus luteum regresses between days 15-18, the colour rapidly changes to yellow, creamy yellow or buff.
* As the corpus luteum regresses between days 15-18, the colour rapidly changes to yellow, creamy yellow or buff.
* The mechanism of luteolysis is not fully understood in the sow.
* The mechanism of luteolysis is not fully understood in the sow.
** Corpora lutea are unresponsive to PGF2
** Corpora lutea are unresponsive to PGF2α until 12-23 days after obulation.
** During luteolysis, corpora lutea are invaded by macrophages.
** Macrophages produce Tumour Necrosis Factor (TNF).
** TNF and PGF2α probably work together to cause luteolysis.
** TNF also inhibits oestradiol production, thus eliminating the luteotrophic source.
* There is rapid regression of corpora lutea at the next oestrus, but throughout the next dioestrus the corpora lutea remain as distinct entities.
* After this they rapidly regress to grey pin-head foci on the ovary.
* During the luteal phase of the cycle, oestrogens are luteotrophic. This may prolong the lifespan of the corpora lutea for several weeks. The result of this is pseudopregnancy.
=== Endocrine Changes during the Oestrous Cycle ===
=== Endocrine Changes during the Oestrous Cycle ===