[Adenylate cyclase activity in human embryo adrenals]

Adenylate cyclase activity was studied histochemically in the human embryo adrenal glands by means of Reik's et al method modified for light microscopy. A negative or very weak reaction to adenylate cyclase in 7--8 week embryos was sharply intensified in 9-week-old embryos, and persisted up to 12 weeks. The reaction was the most intense along sinus capillaries of the provision zone where the enzyme apparently localized in the endothelium and the adjacent cytomembranes of adrenocorticocytes. The latter displayed activity in the areas which had no contact with the endothelium. Manifestation of high adenylate cyclase activity is regarded important for glandular cells differentiation in the adrenal glands.