3β-Hydroxysteroid Dehydrogenase Activity in the Adrenals of Normal and Hypophysectomized Chick Embryos 1

Summary

The adrenals of white Leghorn embryos were examined for histochemically demonstrable 3 β-hydroxysteroid dehydrogenase (3β-HSD) using pregnenolone (P) and dehydroepiandrosterone (DHA) as substrates. Traces of P- and DHA-3 β-HSD activity were seen as early as stage 22 (3.5-4 days) in adrenocortical cells of normal embryos. These activities gradually increased through 8 days of incubation and were evenly distributed throughout the adrenal, however, the P-3 β-HSD was always greater than the DHA-3 β-HSD activity. From 9 days through hatching the adrenals showed a narrow peripheral cortical zone of high P-3 β-HSD and low DHA-3 β-HSD and a large central zone of low P-3 β-HSD and high DHA-3 β-HSD activity. Many of the adrenals of hypophysectomized embryos lacked cortical zones, however, when they did occur the peripheral was always wider and the central smaller than those of normal or shamoperated controls. From 12 through 19 days, peripheral zone P-3 β-HSD activity in hypophysectomized embryos was lower than in controls, except for an increase at 17 and 18 days, and central zone activity was higher than in controls. The peripheral zone DHA-3 β-HSD activity of hypophysectomized embryos during this period was equal to that of controls while that of central zone was lower. The DHA- and P-3β-HSD activity of non-zonated adrenals approximated the peripheral zone levels of zonated adrenals. The DHA-and P-3 β-HSD activity levels of adrenals from hypophysectomized embryos which received adenohypophyseal transplants or exogenous ACTH were at levels of adrenals from controls. Histologically, the adrenals of treated hypophysectomized embryos were similar to those of controls.

The authors express their appreciation to Dr. Russell L. Kutz, Armour Pharmaceutical Company, Kankakee, IL, for the generous supply of ACTH. We also thank Mrs. Lucia Smelte and Mrs.