Sequential changes associated with the degeneration of preovulatory rat follicles

Summary. In 26-day-old rats, follicles capable of ovulation were present 48 h after PMSG injection and they degenerated ifnot exposed to an ovulating dose of HCG. In such follicles 125I-labelled LH bound to the thecal and granulosa cells. By 60 h after PMSG, LH binding to the granulosa cells was reduced by 46 %, although these follicles retained their ability to ovulate. LH binding to the granulosa cells was lost in most follicles by 72 h and ovulation could not be induced. The thecal cells still possessed LH binding sites at 72 h after PMSG. HCG stimulation of these follicles resulted in the disruption of the granulosa and the invasion of blood cells into the antrum