Microvasculature of Mature Bovine Follicles and Its Changes with Ovulation.

Abstract

The present study demonstrated the microvasculature of bovine mature follicles and microvascular changes with ovulation. The microvasculature of bovine mature follicles consisted of 2 capillary plexuses, the inner and outer. The inner capillary plexus consisted of a thick, dense sinusoidal capillary layer and a rough layer of arterioles and venules. Their plexus was character-ized as an independent microcircular unit receiving only one afferent vessel. Microvascular changes with ovulation appeared in the inner capillary plexus. In preovulatory follicles, inner sinusoidal capillaries gave rise to topographical increases in permeability. These phenomena may play an important role in causing the radical increase of follicular fluid pressure and cumulus oophorus discharge. In postovulatory follicles, the inner capillary plexus protruded into the follicular antrum and underwent remarkable angiogenesis to rapidly form the blood vascular bed of the corpus luteum.