Innervation of the zona fasciculata of the adult human adrenal cortex: a light and electron microscopic study.

Autonomic innervation of the adrenal cortex has been demonstrated in several species. Detailed ultrastructural studies on the innervation of the zona fasciculata of the normal human adrenal cortex are lacking. We report herein our observations on the pattern of innervation of the cells of the zona fasciculata of the normal adult human cortex at both the light and electron microscope levels. Postganglionic unmyelinated fibers were observed to descend from a dense capsular meshwork and to be distributed as delicate branches among the columns of endocrine cells. Immunoperoxidase staining confirmed the presence of nerve fibers in the zona fasciculata in a distribution similar to that observed after staining with silver impregnation methods. Ultrastructural findings lent further support to these observations by the demonstration of bundles of unmyelinated fibers with focal enlargements containing terminal boutons with both clear and dense core vesicles in close approximation with the endocrine cells.