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Oestrous Cycle - Anatomy & Physiology (view source)
Revision as of 13:52, 11 September 2008
, 13:52, 11 September 2008→Cyclic Changes in the Ovaries
=== Cyclic Changes in the Ovaries ===
=== Cyclic Changes in the Ovaries ===
==== Anoestrus ====
* In anoestrus, the ovaries are oval and slightly flattened.
* In a medium sized breed, they measure approximately:
** 1.4cm pole-pole
** 0.8 cm from the attached end to the free border
* No follicles can be seen.
* On section, tiny remnants of the corpora lutea of previous cycles are visible as yellow/brown spots.
==== Pro-oestrus ====
* Developing follicles are about 0.5cm in diameter.
* They enlarge until ovulation, where their size is 0.6-1cm.
=== Oestrus ===
* By the time of ovulation, the ovary is enlarged.
* The size of the ovary depends on the number of ripe follicles present.
* The shape of the ovary becomes irregular due to the projection of follicles from its surface.
* The follicle wall is thick, so it is hard to distinguish between follicles and corpora lutea.
* Prior to ovulation, the surface of follicles shows a slightly raised papule. This is about the size of a pin-head. Also, the epithelium covering this papule is brown, whereas the rest of the follicle is flesh-coloured.
* A unique feature of the bitch follicle is the thickness of its wall.
** Due to hypertrophy and folding of granulosa cells which is visible to the naked eye.
** This is evidence of pre-ovulatory luteinization.
* Spontaneous ovulation usually occurs 1-2 days after oestrus onset.
* Most follicles rupture over a period of 48 hours.
* The oocyte can be fertilized for up to 108 hours after ovulation.
==== Dioestrus ====
==== Appearance of the Ovaries on Ultrasound ====
==== Appearance of the Ovaries on Ultrasound ====