IMMUNOCYTOCHEMICAL LOCALIZATION OF SOME LYSOSOMAL HYDROLASES, THEIR PRESENCE IN LUMINAL FLUID AND THEIR DIRECTIONAL SECRETION BY HUMAN EPIDIDYMAL CELLS IN CULTURE

The way in which the human epididymis modifies spermatozoa during thei r sojourn in this structure might be clarified by knowledge of the nat ure of its secretions. We have examined the presence of several lysoso mal hydrolases in human epididymal tissue and fluids, and their synthe sis and secretion by monolayer cultures. Tissues were obtained from me n undergoing orchidectomy for prostatic carcinoma. The enzymes catheps in D and acid alpha-glucosidase were localised in the lysosomes of epi thelial cells from the corpus epididymidis, by an immunocytochemical t echnique, Cathepsin D was also found in epithelial cells of the effere nt ducts within lysosomes, apical vesicles and multivesicular bodies. No immunolocalisation of acid glucosidase in the efferent ducts or on the microvilli of the corpus was demonstrable. Cathepsin D, beta-hexos aminidase (N-acetylglucosaminidase) and alpha-glucosidase were measura ble in the luminal fluid from the human corpus epididymidis; beta-hexo saminidase was secreted into the culture medium by confluent monolayer s of epididymal and efferent duct cells. Immunoprecipitation of cell e xtracts and culture medium of these cultures incubated with S-35-methi onine revealed that the precursors of cathepsin D and beta-hexosaminid ase were synthesized and secreted by such monolayers. Thus, active lyt ic enzymes are secreted by the human epididymis and could modify sperm membranes.