Development of the secretory capacity of the chick embryo adrenal glands.

The secretory capacity of the chick embryo adrenal was investigated at different stages of its development employing a sensitive bioassay for corticosteroids based upon the modifications produced in vitro by these hormones on the height of the chick embryo duodenal mucosa. The adrenal gland cultivated in contact with explants of duodenum and stimulated with increasing doses of ACTH exhibited a mucosal response similar to that produced by corticosterone, both in the slope of the bioassay dose-response curve and in the histological pattern. It has been found that the chick embryo adrenal glands can secrete corticoids from the 5th day onwards by adding ACTH to the culture medium. The basal (unstimulated) secretory capacity of the gland (registered from the 8th day on) is significantly correlated with the total protein content of the adrenals in the different stages of development studied. The maximal secretory capacity of the gland (measured with the dose of ACTH which produces the maximal response) increases steadily up to the 10th day. The rate of increase of corticosteroid secretion due to ACTH is a constant within the interval of development investigated.