[Chronologic and quantitative modalities of luteinization and ovulation in the female rat exposed to FSH action at the beginning of 4-day cycles].

Female Wistar rats were injected with two successive doses of 150 mug FSH on dioestrus I (5 p. m.) and dioestrus II (9 a.m.) of 4-day cycles. Superovulation and formation of an increased number of corpora lutea with included oocytes occurred in these animals. Meprobamate or pentobarbitone injections at 11.30 a.m. et 1.30 p.m. respectively completely blocked ovulation and luteinization phenomena in FSH-treated females. Ovulation normally occurred in FSH-treated females injected with meprobamate at 5.30 p.m. It was concluded that no modification of timing of the 'critical period' resulted from FSH treatment.