Ultrastructure of the silkworm testis. II. Ductus deferens]

Ultrastructure of the silkworm's ducts defferens is described after spermatozoa went out of lobulli testis and after the end of secretion. D. defferens is composed of an external layer of the ring and longitudinal muscles and of an internal layer of glandular cells. Both layers are separated by structurless lamina--tunica propria. Z-discs of irregular form are placed at the borders of sarcomeres. M-lines are absent. Sarcolemma intrudes into the muscle fibers at the level of Z-discs and gives origin to T-system the tubes of which together with sarcoplasmic reticulum form dyades. Structures like intercalate discs are observed in muscle tissue at the level of Z-discs. Glandular cells have unusually developed nucleoli, many ribosomes, lysosome-like and residual bodies. There are comb desmosomes between the glandular cells.