Cytological aspects of the human adrenal cortex development in the course of intra-uterine life

Abstract

Stereological studies were performed on 20 pairs of adrenal glands of human foetuses. The volume of particular adrenocortical zones, average cell volume and number of parenchymal cells were calculated. In 50 to 320 mm crown-rump length (C.-R.L.) foetuses (9-38 weeks of the intra-uterine life) an exponential increase in adrenal gland weight was found. If compared with the earlier period, the rate of increase was evidently higher beginning from the 20th week and depended mainly upon enlargement of the foetal zone, with less marked changes in the glomerulosa-fasciculata zone. The zona glomerulosa (ZG) and the outer zona fasciculata (ZF) began to delineate by the 20th week of gestation. Zona reticularis was not observed in our material. From the beginning of development, fasciculata cell volume was markedly higher than that of ZG cells and lower than foetal zona (ZX) cells. Until the 20th week of intra-uterine life the volume of glomerulosa-fasciculata zone (G-FZ) increased at a slow rate, while the rate of increase in volume of ZX was higher. After 20 weeks the rate of increase in volume of al1 adrenocortical zones was markedly higher (the same as that of the stroma). The volume of stroma in ZX markedly exceeded that in the remaining parts of the cortex. The average cell volume of ZG and ZF remained constant during the foetal period, while the average cell volume of ZX cells increased gradually from the 9th to the 20th foetal week and afterwards remained unchanged. Of interest is the fact that the percentage of ZX cells in the gland remained rather constant during the whole period of observation (about 3540% for ZX and 60-65% for ZG and ZF).