Prostates from eight adult males (age range 17-63 years) were employed in this investigation. Six glands were obtained from multiorgan transplantation donors at the time of organ harvesting, and two additional glands, at routine post-mortem. Microscopic examination has shown that the majority of acini in the peripheral parts of the gland were individually relatively small and lined by an epithelium two to three cells in thickness. In contrast, acini in the central part of the gland were usually large and contained numerous prominent epithelial folds within the lumen. On the basis of morphology, a clear distinction between peripheral and central acini was not observed. The distribution of autonomic ganglia both within and adjacent to the prostate was studied, and nerve cell bodies containing both acetylcholinesterase (AChE) activity and neuropeptide immunoreactivity were identified. The distribution and density of AChE-positive nerves associated with smooth muscle in either the peripheral or central parts of the prostate were indistinguishable. In addition, the majority of acini in peripheral and central regions possessed a rich subepithelial plexus of autonomic nerves. VIP-positive nerve fibers were found in relation to the epithelium lining acini in central and peripheral regions of the gland. In contrast, nerves possessing NPY immunoreactivity occurred only in relation to the smooth muscle trabeculae of the prostate.