Sequential changes associated with the degeneration of preovulatory rat follicles

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Abstract
In 26 day-old rats, follicles capable of ovulation were present 48 h after PMSG [pregnant mare''s serum gonadotropin] injection, and they degenerated if not exposed to an ovulating dose of HCG [human chorionic gonadotropin]. In such follicles 125I-labeled LH [luteinizing hormone] 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. 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.