The ultrastructure of the human bulbo-urethral gland.

The first ultrastructural description of the human bulbo-urethral gland (Cowper's gland) is presented. In light microscopy the secretory cells are cuboidal or cylindrical with a clear cytoplasm and a peripherally located round, rather dense nucleus. Myoepithelial cells are demonstrated in the secretory tissue. The electron microscopy reveals numerous membrane bound secretory granules with dense cored matrix in the cytoplasm. This special composition of the secretory granules corresponds to the analogue glands in ram and bull. The secretory activities seem to be correlated to the development of the gland as a function of sexual maturity of the individual. Secretory granules are found also in surrounding capillaries, which suggests that this gland also has an endocrine function.