Characterization and hormonal regulation of tissue and fluid proteins in the mouse epididymis

The proteins of epididymal tissues and fluids recovered from different regions of the mouse epididymis from a natural population and an inbred line were examined by polyacrylamide gel electrophoresis under denaturing conditions. Two epididymal specific peptides on the order of 88 and 20 Kilodaltons (Kd), undetected in serum and testicular extracts, were identified in the initial segment, caput, corpus and cauda. Another specific 30 Kd peptide was localized in the cauda tissue and fluid. Castration caused the disappearance of the three specific epididymal bands and of a non-specific 34 Kd band. In contrast, a new band appeared at 14.5 Kd. Testosterone propionate administration only restored the three specific epididymal bands and had no effect on the 14.5 peptide. Variations in the staining intensity of the four bands, which were suppressed in castrated animals, were observed after ductuli efferentes ligation.