Ovarian and endocrine responses in the cat after coitus

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Abstract
LH [luteinizing hormone] release leading to ovulation was induced in 17 of 29 estrous periods. The time of ovulation after coitus was determined by histological examination or by observation at laparotomy of ovaries in situ. Histological methods revealed that ovulation was complete in most follicles (9 of 13) at 32 h post coitum and in all follicles that were involved in the ovulatory process by 36 h. When laparotomy was used, no signs of preovulatory change were noted at the first observation time, 22 h post coitum, but in 4 cycles in which the entire process of ovulation was observed, the ovulatory process occurred between 23 and 28 h (3 follicles), 23 and 27 h (2 follicles), 25 and 28 h (3 follicles), 25 and 29 h (3 follicles) post coitum. The 1st ovulatory process noted was complete at 25 h post coitum. In cats, LH release continued over a 16h period before returning to baseline (long surge), values being 616 .+-. 180 ng/ml at 1/2 h and 941 .+-. 154 ng/ml at 2 h post coitum. In 6 cats the LH release pattern was limited to a 4 h period (short surge), values being 537 .+-. 218 ng/ml at 1/2 h, and 353 .+-. 245 ng/ml plasma at 2 h and basal (49 .+-. 18 ng/ml) by 4 h post coitum. Decreased secretion of estrogen by follicles in animals undergoing ovulation was first observed at 16 h post coitum. Coitus induces LH release within minutes in the cat and ovulation begins .apprx. 24 h later and finishes by .apprx. 32 h post coitum. Only 1 coital input can cause LH release for as long as 16-20 h although shorter periods of LH release (4 h or less) can result in ovulation.