Protein secretion by the principal cells of mouse epididymis evidenced by in vitro incorporation of tritiated leucine

The in vitro synthesis and secretion of newly formed proteins were investigated in the principal cells of small pieces of the head and body of mouse epididymis inserted into a modified Rose chamber. Our ultrastructural observations revealed that the cells resumed their normal ultrastructural appearance only after 3 h. Therefore, after preliminary 3-hour culture, the pieces were incubated with tritiated leucine at intervals ranging from 5 min to 6 h. The incorporation of radioactive leucine measured by scintillation counting demonstrated that each of the anatomical segments studied secreted a significant amount of proteins into the culture medium.