PRODUCTION AND SECRETION OF SEX STEROID-HORMONES BY THE TESTES, THE OVARY, AND THE ADRENAL-GLANDS OF EMBRYONIC AND YOUNG CHICKENS (GALLUS-DOMESTICUS)

Testosterone, estradiol, progesterone, and LH levels in adrenals, testes, ovary, and plasma of chicken embryos and chickens were determined with radioimmunoassays. Testosterone contents of adrenal pairs from 17- and 20-day-old male and female embryos were high being around 2 ng. The value rapidly decreased between 1 and 3 days posthatching, reached around 0.1 ng at 3 days of age, and remained at low levels thereafter. Testosterone content of testes on Day 17 of incubation was very low (0.02 ng), but it increased rapidly in pre- and posthatching time and reached the first peak (0.9 ng) at 7 days posthatching. Plasma level of testosterone at embryonic ages was relatively high. Similar results were obtained with the female embryos and female chicks, except for relatively high (0.3-0.4 ng) testosterone content of embryonic ovary. Estradiol content of the ovary from the 17-day-old female embryo was threefold higher than that of the adrenal glands. Estradiol content of the adrenals and the testes from the male embryos was very low and below the detectable level with a exception for the adrenals from the 17-day-old embryo (0.07 ng). Progesterone contents of the adrenal glands from male and female embryos and chicks were relatively high, compared with those of testes and ovary. The concentration in the adrenal reached a peak at 17 days posthatching in both sexes. Plasma LH concentrations of male and female embryos were high, dropped to a low level at hatching, and again increased thereafter. It seems that the adrenal glands have a more important role in the production and secretion of testosterone than the testes or the ovary in the embryonic chicks, and that the embryonic testes are less active than the embryonic ovary for the production of testosterone and estradiol. After hatching the testis or ovary produces and secretes more sex steroid hormones than the adrenal gland does. © 1979.