Expression of cytochrome P450 cholesterol side chain cleavage and 3beta-hydroxysteroid dehydrogenase during embryogenesis in chicken adrenal glands and gonads.

Expression of cytochrome P450 cholesterol side chain cleavage (P450scc) and 3beta-hydroxysteroid dehydrogenase (3beta-HSD) mRNAs was examined in chicken embryonic adrenal glands and gonads between days 4 and 12 of incubation. In situ hybridization analysis showed that 3beta-HSD mRNA appeared on day 5 of incubation in the adrenal glands and on day 6 in the gonads, while P450scc mRNA was expressed on day 7 in both the adrenal glands and the gonads. Cells expressing both enzyme mRNAs were distributed in the steroidogenic tissues of the adrenal glands and in the medullary cords of the gonads. From days 9 to 11 of incubation, P450scc mRNA expression was not found in the majority of both the adrenal glands and the gonads, but was detected again in both on day 12, although 3beta-HSD mRNA was constitutively expressed during this period. Changes in the expression pattern of P450scc mRNA are paralleled by changes in the plasma corticosterone level reported previously. Therefore, it is suggested that P450scc is essential to embryogenesis.