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  • Title: Ontogenetic steroidogenesis by testes, ovary, and adrenals of embryonic and postembryonic chickens (Gallus domesticus).
    Author: Tanabe Y, Saito N, Nakamura T.
    Journal: Gen Comp Endocrinol; 1986 Sep; 63(3):456-63. PubMed ID: 3644766.
    Abstract:
    To elucidate the relationship between steroidogenesis and sex differentiation in the chicken, pituitary and plasma LH, plasma, testicular, ovarian, and adrenal testosterone, estradiol-17 beta, estrone, and progesterone; and plasma and adrenal corticosterone and cortisol concentrations from 8-, 10-, 12-, 14-, 16-, 18-, and 20-day-old embryonic and 1-, 3-, 7-, and 14-day-old chicks were determined by radioimmunoassay. The plasma LH level was high in 10- to 12-day-old embryos and decreased with advancing age. No sex difference was observed in plasma, testicular, and ovarian testosterone concentrations at embryonic ages. After hatching, a higher testosterone level was observed in the testes than in the ovary, while a similar testosterone level was observed in the plasma of both sexes. Both plasma estradiol-17 beta and estrone concentrations were significantly higher in the female embryo than in the male embryo. Higher values of the two estrogens were observed in the left ovary of the female embryo than in the testes of the male embryo, and the estradiol concentration in the female embryonic ovary was much higher than the testosterone concentration in the male embryonic testes. No sex difference was observed in plasma progesterone, corticosterone, or cortisol. Both plasma and adrenal corticosterone concentrations reached peaks at hatching time. These results indicate that the chicken embryonic ovary is much more active in production and secretion of sex hormones with special reference to estrogenic hormones than are the embryonic testes. It is strongly suggested that the sex of the avian species is basically male, having homozygosity of sex chromosomes (ZZ), and that the estrogens secreted by the embryonic ovary have important roles in female sex differentiation.
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