Light and electron microscopic immunohistochemistry on the localization of cytochrome P-450 of the side chain cleavage system and of cytochrome P-450 of 11 beta-hydroxylase in the bovine adrenal cortical cells.

In order to know the mechanism of steroid hormone biosynthesis, the localization of cytochromes P-450 of cholesterol side-chain cleavage enzymes (P-450SCC) and P-450 of 11 beta-hydroxylase (P-450(11)beta) were studied in bovine adrenal glands by light as well as electron microscopic immunohistochemistry, using monoclonal antibodies. With light microscopy the cytoplasm of the glomerulosa cells was faintly immunostained, while that of the fasciculata-reticularis cells was intensely immunostained by both monoclonal antibodies for cytochrome P-450SCC and cytochrome P-450(11)beta, though the capsular connective tissue cells and the adrenal medullary cells were entirely negative for these reactions. Electron microscopic immunohistochemistry revealed that the positive reaction products for cytochromes P-450 were present on the matrix side of the inner mitochondrial membrane including the tubulovesicular cristae of the cortical cells, and especially of the fasciculata and reticularis cells. The present results indicate that both cholesterol side-chain cleaving enzymes and 11 beta-hydroxylase are present in the inner mitochondrial membrane of bovine adrenal cortical cells.