Bioscientifica Proceedings

Summary. Ultrasound imaging has shown that cattle exhibit 2 or 3 waves of follicular development during an oestrous cycle. The waves consist of the contemporaneous appearance, about every 7 days, of a group of follicles ≥ 5 mm in diameter. One follicle gradually becomes larger than the rest (i.e. dominant). There are several lines of evidence suggesting that the waves occur regularly under conditions of basal LH and FSH. (1) Cycles with 3 waves of follic...

Numerous corpora lutea form from the multiple follicles that ovulate during the oestrous cycle of pigs. Vascular elements invade the follicle from the theca compartment, first centripetally, and subsequently by lateral branching of centripetal veins and arteries. The vessels are the vehicle for dispersion of steroidogenic theca cells throughout the corpus luteum. Mitosis occurs in both the theca and granulosa layers before ovulation, and in luteal cells well into the lut...