Basal epithelial cells of human prostate gland are not myoepithelial cells. A comparative immunohistochemical and ultrastructural study with the human salivary gland.

The hypothesis that basal epithelial cells of the human prostate are of myoepithelial origin was investigated using immunohistochemical and ultrastructural methodologies. The immunohistologic analyses show significant phenotypic differences between prostatic basal cells and myoepithelial cells of the salivary gland. Although both cell types stain intensely with the 312C8-1 monoclonal antibody, only true myoepithelial cells demonstrated significant amounts of muscle-specific actin as decorated by the HHF35 monoclonal antibody. Furthermore, using double-labeling experiments, the prostatic basal cells were strongly decorated with a fluorescein-tagged basal cell-specific keratin but were negative with the rhodamine-tagged phalloidin, a chemical that binds specifically to actin microfilaments. Ultrastructural studies also showed an absence of thin microfilament bundles, dense bodies, and micropinocytotic vesicles in the prostatic basal cells. The current investigations show that the prostatic acini do not have a basal myoepithelium. Although some authors have suggested a stem cell role for prostatic basal cells, the weight of experimental work argues against this hypothesis. The exact role of the basal epithelial cells of the prostate is not known, although they may serve endocrine, paracrine, or other regulatory functions and may be involved in modulating signals between prostatic stroma and epithelium.