The present study is the first to provide evidence that episodic release of LH during the 48 h before the preovulatory surge of LH is important for development of the CL in cattle. Inhibition of LH release for the 48 h preceding the preovulatory surge of LH resulted in development of a CL smaller in diameter than those from females of the control group or from females in which episodic release of LH was inhibited coincident with initiation, or starting 48 h after initiation, of the preovulatory surge of LH. The small-er-diameter CL of females in this group indicates that the episodic release of LH pulses during the period preceding the preovulatory surge of gonadotropins is required for maturation of the follicle to allow for development of a CL of typical size.
Sustained episodic stimulation of ovarian follicles by LH pulses may permit maturation of the follicle before the preovulatory surge of LH, and this is consistent with the concept that there is preparation of theca and granulosa cells for luteinization before ovulation of the dominant follicle. This may explain why two females in the Ant —2 group did not ovulate despite having follicles similar in diameter to those of other females that did ovulate.