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Oestrous Cycle - Anatomy & Physiology (view source)
Revision as of 09:27, 11 September 2008
, 09:27, 11 September 2008→Cyclic Changes in the Ovaries
* The luteolytic mechanism is similar to in the cow.
* The luteolytic mechanism is similar to in the cow.
** At the end of dioestrus, under the influence of oestradiol and progesterone, there is an increase in the number of uterine oxytocin receptors.
** At the end of dioestrus, under the influence of oestradiol and progesterone, there is an increase in the number of uterine oxytocin receptors.
** At the same time, the corpus luteum produces oxytocin, which stimulates PGF2. PGF2 then acts to stimulate the release of oxytocin in a feedback loop mechanism.
** At the same time, the corpus luteum produces oxytocin, which stimulates PGF2α. PGF2α then acts to stimulate the release of oxytocin in a feedback loop mechanism.
* The first corpora lutea formed after the first ovulation at the start of the breeding season have a shorter lifespan than subsequent ones.
* In twin ovulations, the two corpora lutea can occupy the same or opposite ovaries.
* During pregnancy:
** The corpus luteum is 0.7-0.9 cm in diameter.
** It is pale pink in colour
** The central cavity that is seen in cyclic corpora lutea has disappeared and is filled with white tissue.
* Ovulation with corpus luteum formation but without heat may occur in the anoestrus period. This is known as spurious ovulation.
* The number of ova shed at each oestrus is dependent on genetic and nutritional factors.
=== Endocrine Changes during the Oestrous Cycle ===
=== Endocrine Changes during the Oestrous Cycle ===