Experimental research on the morphofunctional differentiation of the rat ventral prostate: roles of the gonads at birth.

In the male rat, a dramatic increase in serum testosterone (T) of testicular origin occurs during the first few hours of postnatal life. This experiment sought to determine whether this increase affects the physiology of the adult rat ventral prostate. Male rats were castrated at the time of caesarean delivery performed at different precise stages between 21 days and 22 days of gestation (0h males).

[Variations in the testicular response to HCG during the perinatal period in the rat: influence of estrogens].

The variations of the testicular responsiveness to hCG and the implication of the maternal estrogens in the functioning of the testes were studied in the perinatal male rat. Male rat fetuses treated with hCG at the end of gestation failed to show an increase in serum testosterone (T). The lack of testicular responsiveness to hCG in the fetus is neither due to anesthesia nor to a blocking effect of estrogens directly on the testes.

Changes in plasma testosterone levels during the peri-hatching period in the chicken.

Blood was obtained by heart puncture from 19-day-old Black Sex link chicken embryos and from Black Sex link chickens at 1.5, 6, or 24 h post-hatching. Plasma testosterone was determined by gas chromatography-mass spectrometry associated with stable isotope dilution.

The neonatal testosterone surge: a comparative study.

In the rat an abrupt discharge of testicular testosterone in the newborn male figures prominently in the development of mechanisms controlling gonadotropin secretion, sexual behavior, and also promotes the functional differentiation of the accessory sex glands. In this study we detail the temporal characteristics of this surge in the rat, and we provide comparative data documenting a similar surge-like appearance of testosterone in neonatal male mice, recently foaled male horses, and newborn human infants. Although the physiological and behavioral significance of this phenomenon for species other than the rat remains to be determined, the apparently ubiquitous appearance of the neonatal testosterone surge suggests that it may be of special significance in the sexual differentiation of many mammalian species.

Sex differences in serum luteinizing hormone and testosterone in the human neonate during the first few hours after birth.

Blood was obtained from human male and female neonates within a few minutes after birth, and at intervals thereafter for up to 21 h. Serum LH was substantially higher at birth for boys than girls. For most boys, serum LH fell precipitously during the next hour; serum LH remained low for the remainder of the period sampled in both boys and girls.