REGULATION OF MOUSE EPIDIDYMAL EPITHELIUM IN-VITRO BY ANDROGENS, TEMPERATURE AND FIBROBLASTS

The epididymal epithelium provides the microenvironment for sperm matu ration. However, the molecular basis of epididymal function is still p oorly understood because of the limitations of in vivo systems. For th is reason, we have developed an in vitro culture system for mouse epid idymal epithelial cells. Cells were purified by enzymatic digestion an d centrifugation through a Percoll gradient, and plated on inserts coa ted with a replacement basement membrane. Cultured cells maintained ul trastructural and immunocytochemical features of epithelia, but did no t retain the androgen responsiveness of epididymal cells (as judged by androgen receptor detection and secretion of specific markers) unless cocultured with fibroblasts. The androgen receptor was detected in th e nuclei of epididymal epithelial cells only when grown with epididyma l fibroblasts in the subjacent chamber. Moreover, specific epididymal secretory proteins were secreted only when epithelial cells were cultu red in the presence of both androgens and fibroblasts at 32 degrees C. These results highlight the importance of cell-cell interaction, as w ell as temperature regulation in the physiology of the epididymis. The y also establish the existence of two independent pathways in the diff erentiation of these cells. The first, leading to the expression of ep ithelial characteristics, is fibroblast-independent, whereas the secon d, conferring tissue-specific features, depends upon coculture with fi broblasts.