Importance of perinatal testosterone in sexual differentiation in the male rat.

Testosterone secretion in the male rat was high during the late fetal and immediate postnatal periods. It then showed a rapid decrease 3h after birth and remained low until puberty. Male rats from mothers given daily injections of an antibody to testosterone during the week before delivery displayed an LH peak when they were adult, orchidectomized and implanted with oestradiol.