Ovarian Changes over the reproductive cycle

Description of events:
Following a wave of folliclular development some 10-20 follicles develop on each ovary into full follicles (fluid filled structures) which at 1cm in size, rupture and release their egg. The ruptured follicle fills with blood –the corpora haemorrhagica From this follicle and blood clot a organise into a solid structure the corpora lutea. This structure produces progesterone. This structure is either maintained throughout pregnancy or regress after 18 days and allow a new wave of follicles to develop and a new cycle develops. The old corpora lutea develop into a small hard corpora albicans which slowly regress.
Detail of ovarian structures:
This particular ovary, at the end of the reproductive cycle, demonstrates many of the features which can be recognised on a normal ovary. During the cycle the major differences is the sizes of structures. In the pig a mature follicle measures 1 cm in diameter and a mature corpora lutea is also a 1 cm in size.