Human prostatic endocrine-paracrine (APUD) cells. Distributional analysis with a comparison of serotonin and neuron-specific enolase immunoreactivity and silver stains.

Prostatic endocrine-paracrine (PEP) cells from the prostates of 25 radical cystectomy specimens were studied using serotonin and neuron-specific enolase immunocytochemistry and argyrophil and argentaffin silver stains. Three populations of PEP cells were identified as follows: (1) serotonin-positive only, (2) serotonin-positive and argyrophil-positive (the largest population), and (3) serotonin-positive, argyrophil-positive, and argentaffin-positive. Neuron-specific enolase immunoreactivity correlated closely with serotonin immunoreactivity. The entire PEP cell cytoplasm was serotonin and neuron-specific enolase immunoreactive, while the silver stains only stained the granulated cytoplasm. The PEP cells were present in all areas of all prostates with a surprisingly large number in the large periurethral ducts with somewhat fewer PEP cells in the prostatic urethra and smaller ducts and ductules. The peripheral acini generally contained the smallest number of PEP cells. Prostatic endocrine-paracrine cells were of the open (luminal extension), closed, and dendritic types.