FACTORS DETERMINING THE SEX DIFFERENCES IN PITUITARY AND SERUM FSH-CONTENTS AFTER GONADECTOMY

Abstract

The FSH-content in the serum and pituitary glands of male and female rats was estimated after gonadectomy in adult animals or on the first day of life, and in sham-operated animals. The serum content of non-gonadectomized male and female rats is virtually the same. Gonadectomy, whether performed early or late, produces a similar increase in the serum FSH-content. In male rats it reaches a higher level than in females. The same response to early and late gonadectomy suggests that the sex difference which appears after gonadectomy may be due to genetic factors. The pituitary content of non-gonadectomized male rats is much higher than that of females. After early gonadectomy the pituitary FSH-content in males equals that of females at a level below that of normal males. A similar content is found in females after late gonadectomy, whereas in males the content is higher and equals that of normal males. This indicates that the sex difference in hypophyseal FSH-content of rats gonadectomized during adult life is hormonally conditioned. It may be due to fixation of the effect of endogenous androgen.