[Effect of the genotype on the reactivity of the hypothalamo-hypophyseal-adrenal system of chick embryos]. / Vliianie genotipa na reaktivnost' gipotalamo-gipofizarno-adrenalovoi sistemy kurinykh émbrionov.

Studies have been made on embryos of two hen lines selected by their reaction to cold stress (highly and lowly reactive ones). The adrenals of 16-day chick embryo react to the injection of the ACTH by synthesis of glucocorticoids and by their secretion into the blood. The rate of this reaction is higher in highly reactive line of hens. The hypothalamo-hypophyseal-adrenal system in chicks begins to respond to the increase in the environmental temperature by the synthesis and secretion of glucocorticoids already during embryo-genesis. In 18-day embryos, this reaction is more evident in highly reactive line.