OESTROGEN INDUCED SYNTHESIS OF A PROTEIN IN AVIAN LIVER

Oestrogens have a dual role. In organisms exposed to the hormone for the first time, they act as differentiating agents directing the division and recruitment of precursor cells to those competent to make hormone dependent products. Data are given for the induction of the synthesis of an egg yolk protein, phosvitin, in immature pullets and roosters. The hormone is also required for the expression of the differentiated function in the committed cells. The paper also reviews briefly the salient features of the action of oestradiol in the ovariectomized rat uterus. The hormone is recognized by "receptor" proteins present in the cytoplasm. The hormone-receptor complex migrates rapidly to the nucleus. A derepression of RNA synthesis is observed as an early event.