Fine structure of the modified sertoli cells in the terminal segment of the seminiferous tubules of the bull,ram and goat

The ultrastructure of the epithelial cells in the terminal segment of the seminiferous tubules was studied in the bull, ram and goat. These cells were characterized by membrane-bounded spaces and intercellular dilatations, and abundant microtubules and microfilaments. The presence of vacuolated nucleoli and typical inter-Sertoli cell junctions in the cells of the terminal segment confirms the concept that these cells are actually modified Sertoli cells. Ligation of the efferent ductules in the bull for 24 h had no harmful effect upon the blood-testis barrier in the terminal segment.