[Steroidogenesis in epithelial cells of rat epididymis]

Studies were performed on cultured epithelial cells of the caput and cauda of epididymis stemming from male rats of inbred Wistar strain. The cultures were conducted on a full medium enriched with 5% fetal calf serum in the presence or without exogenic androgens-T and DHT. The cells were identified by means of immunohistochemical reactions with the use of monoclonal antibodies against cytokeratin and desmin (Fig. 1, 2). All cells in the culture showed positive reaction to cytokeratin. At the same time there was a lack of desmin-positive cells. Through secreting the proteins, glycoproteins, glycolipids, phospholipids and number of other substances the epithelial cells of epididymis create an environment for maturating and storing of spermatozoa in lumen of the duct. Synthesis of these substances is possible thanks to the expression of genes defined for a given zone of epididymis, the expression being mainly regulated by androgen, although a share of estrogens is also evidenced in this process. The cytoplasm of epithelial cells of epididymis fails to reveal the presence of secretory granules, while the mechanism of releasing the secretion still continues to be controversial. There are also some and unverified suggestions about the capability of these cells to synthesize androgens. In connection with what was mentioned above, the objective of the work was to establish the mode of releasing the secretions by cultured epithelial cells of epididymis as well as to determine whether these cells synthesize androgens and if they may be the source of estrogens. Electron-microscopic observations disclosed a rich content of rough endoplasmic reticulum and structures similar to secretory units produced from concentrically arranged membranes encircling cytoplasm fragments in their interior (Fig. 10B, 14, 15A). There were protrusions of cytoplasm on the surface of cells. Released secretion was present between the cells. The apocrine way of releasing was confirmed also by scanning electron microscope. Numerous granular protrusions were released into the intercellular space (Fig. 19). The process of synthesis and release of secretion was androgen-dependent. Cells cultured without addition of exogenic androgens were characterized by disorganization of organelles and reduction of their number, particularly rough endoplasmic reticulum. The surface of cells was prevalently smooth, deprived from protrusions (Fig. 21). Very close neighbourhood, and sometimes a direct contact of lipid droplets and mitochondria with lamellar cristae as well as the presence of smooth endoplasmic reticulum observed in cytoplasm of cultured epithelial cells of epididymis, suggest their similarity to steroidogenic cells (Fig. 11A, 12). This is also indicated by the finding that these cells reveal the presence of active enzymes of the steroidogenesis pathway, 3 beta-HSD and 17 beta-HSD exhibited in histochemical reactions (Fig. 8, 9). RIA determination of hormones in the medium, wherein the epithelial cells had been cultured showed that the said cells synthesized and released DHEA, A and T, but in low and sometimes trace concentrations (Tab. 1-3). Lack of progesterone in medium of the cells on the 3rd and 5th days of culture indicates that the synthesis of testosterone and earlier forms of androgens proceeds using delta 5 metabolites, as it takes place in human testis. The cells' medium on the 3rd and 5th days of culture was found to disclose high concentration of 17 beta-estradiol (E2) (Tab. 4). E2 concentrations were always higher when the cells were grown without the addition of exogenic androgens. In this cases the cytoplasm of the cells displayed depolymerization of microtubules, which enhances the approximation to each other of structures participating in steroidogenesis and translocation of substrates and products of the consecutive stages of steroidogenesis. (ABSTRACT TRUNCATED)