Development of adrenal cortical zonation and expression of key elements of adrenal androgen production in the chimpanzee (Pan troglodytes) from birth to adulthood

• Adrenal sections from 27 autopsied chimpanzees (birth – 31 years) were immunostained.
• Chimpanzee fetal zone (FZ) expressed CYP17, SULT2A1, and Cytochrome B5 but not HSD3B.
• FZ involution was paralleled by reduced expression of SULT2A1 and Cytochrome B5.
• Z reticularis development was evident by 3 years and had similar expression to the FZ.
• Adult chimpanzee and human adrenals share many similarities.

The basis for the pattern of adrenal androgen production in the chimpanzee, which resembles that of humans, is poorly defined. We characterized the developmental zonation and expression of elements of the androgen biosynthetic pathway in the chimpanzee adrenal. The newborn adrenal contained a broad fetal zone (FZ) expressing CYP17, SULT2A1, and Cytochrome B5 (CB5) but not HSD3B; the outer cortex expressed HSD3B but not SULT2A1 or CB5. During infancy, the FZ involuted and the HSD3B-expressing outer cortex broadened. By 3 years of age, a thin layer of cells that expressed CB5, SULT2A1, and CYP17 adjoined the medulla and likely represented the zona reticularis; the outer cortex consisted of distinct zonae fasiculata and glomerulosa. Thereafter, the zona reticularis broadened as also occurs in the human. The adult chimpanzee adrenal displayed other human-like characteristics: intramedullary clusters of reticularis-like cells and also a cortical cuff of zona fasiculata-like cells adjoining the central vein.