Development of zonular patterns in the human adrenal gland

Microscopic studies of human adrenal glands from 58 autopsy specimens, ranging in age from one month gestation to 69 years, revealed a pertinent developmental pattern in the establishment of definitive zonation. This pattern was established using the following criteria: (1) relationship of age to the developing zones; (2) times of formation of definitive zonation; and (3) the morphological determination of developmental patterns based on staining characteristics. Using these criteria, development was divided into five phases: (1) condensation of coelomic epithelium; (2) secondary proliferation of coelomic epithelium; (3) finding of PAS‐positive material within the fetal cortex; (4) decline and disappearance of the fetal cortex; and (5) establishment and stabilization of the definitive zonular patterns. Significant features occurring in this development were: (1) the origin of both permanent and fetal cortex from proliferation of coelomic epithelium; (2) the appearance of PAS‐positive granules surrounding a homogenous mass in the fetal cortex and the zona reticularis during maturation and organization; and (3) the gradual establishment of definitive zones by proliferation of the permanent cortex, maturation of the fetal cortex, and growth of the medulla; with the adult structure of the adrenal gland achieved by the eleventh to fifteenth year without any apparent major involution or hemorrhage.