Intraepithelial lymphocytes in the male reproductive tract of rats and rhesus monkeys.

Although lymphocytes are never present in 'normal ' seminiferous epithelium, they are found in the terminal portions of the seminiferous tubles near their junctions with the tubuli recti. Intraepithelia lymphocytes are also found in the tubuli recti testis, ductuli efferentes, epididymis and ductus deferens. The ultrastructural morphology of these cells closely resembles that of the intraepithelial lymphocytes in the intestinal mucosa and those obtained from the lymph nodes, spleen blood and thoracic duct. The mucleus is spherical and is characterized by clumps of chromatin near the nuclear membrane. A thin rim of cytoplasm is usually found, and is remarkably free of most cell organelles except for free ribosomes. Frequently, a blunt cytoplasmic process can be seen extending from one end of the cell. Membrane-bounded granules and other dense bodies are occasionally encountered in the cytoplasm. The possible functional significance of intraepithelial lymphocytes in the male reproductive tract is discussed.