The development of the early-androgen syndrome in the female rat

The gonadal functions of male and female individuals are mainly regulated by two gonadotrophic hormones, folliclestimulating hormone (FSH) and luteinizing hormone (LH) , both secreted by the pituitary. In spontaneously ovulating mammals (e.g. rat and man) periodic discharges of these hormones, resulting in ovulation, are characteristic of the female, whereas similar periodic discharges have never been observed in the male. Every four or five days female rats show a peak in serum LH on the afternoon of the day preceding ovulation (the day of prooestrus), which coincides with an increase in serum FSH. The high FSH level is maintained till the afternoon of oestrus (Gay et al, 1970; Daane and Parlow, 1971). The serum LH peak normally results in ovulation of a number of follicles, which are transformed to corpora lutea. In rats these processes recur every four or five days.