Ultrastructural localization of zinc ions in the rat prostate: An autometallographic study

BACKGROUND The prostate contains high amounts of free zinc ions which are excreted into the seminal fluid. The extra‐ and intracellular distribution of zinc ions using the highly specific autometallographical (AMG) method is described. METHODS Prostates from sulfide‐perfused rats were excised, and the ZnS crystals were silver‐enhanced to sizes detectable by the electron and light microscope. RESULTS AMGZnS grains were found primarily in the acinic lumen of the lateral lobes. The dorsal lobe stained only faintly, while the ventral lobe was void of grains. At ultrastructural levels, the presence of zinc ions was confined to apical secretory vesicles and lysosome‐like structure of the epithelium of mainly the lateral lobes. CONCLUSIONS We suggest a constant secretion of zinc ions from the epithelial cells into both the acinar lumen and the intercellular canaliculi, and that the zinc enriched secretory cells in the prostate belong to a system of glandular cells that uses zinc ions to aggregate macromolecules to be excreted. Prostate 31:125–130, 1997. © 1997 Wiley‐Liss, Inc.