Correlative study on sex differences in pituitary luteinizing hormone content and the number of immunoreactive luteinizing hormone cells in perinatal rats.

Sex differences in both pituitary luteinizing hormone (LH) content and the number of LH cells were correlatively studied in perinatal male and female rats. In the fetal pituitaries of late gestation, no sex difference was observed. On the day of birth, LH content and LH cell numbers were significantly greater in female than in male rats. Both of the two sex differences became more pronounced during the 1st and 4th postnatal days. Hormone synthesis and proliferation of pituitary LH cells are probably suppressed by testicular steroids in perinatal male rats.