THE INDUCTION OF OVULATION IN IMMATURE RATS TREATED WITH PREGNANT MARE'S SERUM GONADOTROPHIN AND HUMAN CHORIONIC GONADOTROPHIN

¹ Medical Research Council Clinical Endocrinology Research Unit, University of Edinburgh

Studies have been made on ovarian and uterine weight, the occurrence of follicular hæmorrhage and ovulation, and the number of ova shed in the intact immature rat treated with pregnant mare's serum gonadotrophin (PMSG) and human chorionic gonadotrophin (HCG) either alone or in combination.

Both PMSG and HCG when given alone were capable of inducing ovulation. This event was associated with uterine stimulation but generally occurred in the absence of marked ovarian weight increase or follicular hæmorrhage.

The administration of PMSG followed by HCG produced ovulation over a wide dosage range of both hormones. With low dose levels of PMSG the number of ova shed was independent of the dosage of HCG. However, this was not the case at higher dosages of PMSG, the injection of which was associated with marked ovarian weight increase and follicular hæmorrhage.

The mechanism by which PMSG and HCG exert their effects on the ovary is discussed.

Note:

The authors wish to thank Organon Laboratories Ltd. for supplies of PMSG and HCG.