Progesterone, its A/B cis reduction and delta aminolevulinic acid synthetase in the developing hen.

In steroidogenic tissues of the developing hen, specially in the right ovary, 5 beta reductase (Rase) increases after hatching. delta aminolevulinic acid synthetase (ALAs) in these tissues is more active than hepatic ALAs during most embryonic stages. But after hatching, only hepatic and adrenal ALAs increase sharply; ALAs increases only moderately in the left ovary and descends to very low values in the right one. A relationship between ALAs and Rase curves during embryonic development of the left ovary and the adrenal suggests that 5 beta pregnanedione is a natural inducer of ALAs in these functional endocrine glands, at least during their embryonic stages.