Testosterone secretion of rat and mouse Leydig cells cultured at plates precoated with collagen taken from male and female rats.

Testosterone secretion by Leydig cells in vitro was significantly higher on male collagen coated, than on female collagen coated plates. The castration of male rat-donors of collagen demonstrated that 2 months of androgen deprivation eliminated the effect.

[Development of hypothalamic control over thyrotropin secretion during human prenatal life]. / Razvitie gipotalamicheskogo kontrolia nad sekretsiei tireotropina v prenatal'noi zhizni cheloveka

It was shown in the tissue culture experiments that the human hypophysis secreted autonomously the thyrotrophin during the last three fourths of the prenatal life. The intensity of secretion is the highest in the end of the first third of this period, then it decreases, but during the last third it increases reliably again. During the second half of development the level of thyrotrophin in female foetuses in reliably higher than in the male ones. In the beginning of the second third of prenatal life, the hypothalamic factors decrease the autonomous thyrotrophin secretion twice in foetuses of both the sexes. In the end of the second third, sexual differences appear in their effect; they decrease reliably the autonomous thyrotrophin secretion in the male foetuses, whereas no such effect is observed in the female ones. The stimulating effect of the hypothalamic thyrotrophin releasing hormone manifests itself during the last third of prenatal life in foetuses of both the sexes. During the second half of prenatal life, the thyrotrophin concentration in blood of female foetuses is also reliably higher than in male foetuses. There is a positive correlation in female foetuses between the thyrotrophin concentration in blood and the level of hypophysial secretion under the effect of hypothalamic factors. Thyrotrophin is found in the cranial fluid of foetuses. In some cases its concentration in the cranial fluid is higher than in the blood. No correlation was found between the levels of the hormone in fluid and blood in female foetuses; a positive correlation was found in male foteuses.

[Sex differences in the secretory activity of the gonads and in their sensitivity to gonadotropins in early ontogenesis of rats]. / Polovye razlichiia sekretornoi aktivnosti gonad v chuvstvitel'nosti k gonadotropinam v rannem ontogeneze u krysy

The secretion of estrogens by the ovaries of foetal (15-19 days of gestation) and newborn rats in organ cultures was not detected by fluorimetry when the ovary was taken prior to the onset of folliculogenesis. The time schedule of the process of folliculogenesis in organ culture corresponded to that in vivo. Estrogens were detected in the medium when folliculogenesis was fully established in organ cultures. The secretion began spontaneously and was not affected by the addition of gonadotropins to the medium. On the contrary, the secretion of androgens by the testes of foetal (17-19 days of gestation) and newborn rats in organ cultures was constantly detected by the competitive protein-binding assay. The addition of gonadotropins to the culture medium increased the level of androgen secretion by foetal and newborn rats.

PIP: The influence of gonadotropins on the specific secretory activity of the gonads of rats was studied under cultivation. The ovaries and testicles were cultivated in rats from 15-day-old fetuses to newborn, over the course of 4-21 days with and without the addition of gonadotropins. Under these conditions the secretion of estrogens by the ovaries was detected only after the appearance of the 1st follicular cells. The addition of gonadotropins did not speed up this process, although it did increase the intensity of it to an insignificant degree. The secretion of the sex hormones in the testicles was observed at all phases of development studied (from the 17th day of the fetus until birth). The addition of gonadotropins intensified the secretion of androgens of the seminal glands throughout the entire period.

Responsiveness of the ovary to gonadotrophins in pre- and perinatal life: oestrogen secretion in tissue and organ cultures.

Secretion of oestrogen by the ovaries of foetal (15-19 days of gestation) and newborn rats in organ and tissue culture was not detectable by fluorometry when the ovary was taken from foetuses before folliculogenesis had occurred. In organ cultures of ovaries, the time of folliculogenesis corresponded with the normal timing of folliculogenesis in vivo. In tissue cultures the process of formation of follicles was delayed. Oestrogens were present in the medium when folliculogensis was fully established in the cultured foetal ovaries. Secretion began spontaneously and did nto depend on the addition of gonadotrophins to the medium. The addition of gonadotrophins the the culture medium did not effect the level of oestrogen secreted by the foetal and newborn rat ovaries during the period of incubation (2-3 weeks).