[Concentrations of estradiol in the quail magnum during sexual development. Relation to the levels of cytoplasmic receptors for this hormone].

Estradiol 17 beta concentration and cytoplasmic estradiol binding sites were determined in the magnum of immature and developing female Quail. In the immature magnum, estradiol concentration per gram of tissue was 26 times higher than in the plasma. Early sexual development was correlated with an increase in plasma and magnum concentrations of estradiol and of cytoplasmic binding sites in the magnum. However, the ratio of binding sites concentration to that of intra-tissue of estradiol, and the intracellular distribution of estradiol (cytoplasm versus nucleus) were similar in immature and developing Quail. The results indicate that the presence of estradiol and of binding sites in the target cells of the magnum are not sufficient to induce cell proliferation.