Differentiation and zonation of the adrenal cortex

Abstract

The recent advances in molecular endocrinology have resulted in clearer understanding of the process of differentiation and zonation of the mammalian adrenal cortex. Precursors of steroidogenic tissues appear in a rat embryo at an early stage of gestation, cleaving into the adrenal and gonad portions at midgestation. During the late stage of pregnancy, cortical precursor cells in the adrenal primordium become able to produce corticosterone, aligning themselves under the possible influence of developing microvasculature, and the medullary cells establish themselves at the central part of the gland. The completion of the fasciculata zone and the aldosterone-producing glomerulosa zone occur around term. The functionally undifferentiated zone between the zonae glomerulosa and fasciculata of the adult cortex seems to contain cortical stem cells, which migrate into the fasciculata zone after a space of time. The results obtained by the regeneration experiments as well as the transplantation experiments corroborate a notion that cells attached to the adrenal capsule could change their phenotypes under specific physiologic conditions.