OVULATION FOLLOWING VAGINAL STIMULATION IN A SPONTANEOUS OVULATOR AND ITS IMPLICATIONS

Abstract

SUMMARY Ovulation was blocked in pregnant mare serum-treated immature rats by treatment with chlorpromazine. Reflex ovulation and hence luteinizing hormone release was induced by three procedures: (a) placing male rats with the treated females overnight, (b) mechanical stimulation of the vagina and cervix with a glass rod, and (c) electrical stimulation of the uterine cervix. Mating or mechanical stimulation induced ovulation in 77 and 82% of the rats, respectively. Electrical stimulation was least effective, causing ovulation in only 50%. The average number of ova released and the percentage of rats ovulating was found to be a function of the amount of mechanical stimulation with the glass rod. Pelvic neurotomy abolished the reflex ovulatory response. The stronger response obtained by coitus or mechanical stimuli indicated the possibility of receptor sites in the vaginal wall. This assumption was supported by the finding of penile spines in the rat. A survey of the literature indicates that penile spines are present in a variety of mammalian orders including the primates. The evolutionary relationships and implications of the existence of penile spines and reflex ovulation are discussed. It is suggested that man, like the rat and probably other species which ovulate spontaneously, also has the ability to ovulate after stimulation of the vaginal tract.