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Cadmium induces morphological and functional changes of cells in the rat epididymis

The function of epididymis is to accumulate and store spermatozoa, and to generate conditions for their maturation. During their passage through epididymis, spermatozoa are immobile due to acidic environment in the duct lumen. The respective cells and cellular mechanisms responsible for this acidification have been poorly defined. We have recently indicated clear cells as likely contributors to this process (1). Cadmium (Cd) is a wellknown pollutant strongly toxic to the male reproductive tract. In experimental animals, subchronic Cd administration causes atrophy of testes and epididymi, impaired spermatogenesis, and loss of acidification in the epididymis (2). In order to further describe the cells that contribute to proton (H+) secretion, and to explain the Cd-induced loss of acidification in the epididymis, we immuno-histochemically characterized organs in control and Cd-intoxicated rats. Four mm thick cryosections of the in vivo fixed tissue were studied by indirect immunofluorescence (3) using monoclonal and polyclonal antibodies to specific subunits of the vacuolar H+-ATPase (V-ATPase), carbonic anhydrase type II (CA II), and Na/K-ATPase. We confirmed the clear cells as possible H+-secreting cells in the adult rat epididymis. These cells, being high columnar in the head, low columnar in the body, and cuboidal in the tail of epididymis, exhibited a heavily labeled V-ATPase in the apical domain and cytoplasmic localization of CA II. They, however, lacked basolateral staining with the anti-Na/K-ATPase antibody. Following subchronic Cd-treatment in rats, all clear cells along the epididymis transformed into high columnar and showed a diffuse cytoplasmic localization of the V-ATPase, whereas the staining pattern with the anti-CA II and anti-Na/K-ATPase antibodies remained unchanged. Cells of similar shape and appearance were detected in the epididymi from pre-pubertal rats. We conclude that a) clear cells with the apically-located V-ATPase are most probably responsible for acidification in the epididymal duct, and b) Cd induces regression of these cells into pre-pubertal (immature) non-secretory form. References: 1. Brown D, Lui B, Gluck S and Sabolic I, Am. J. Physiol. 263: C913-C916, 1992 2. Caflisch C R and DuBose T D, J. Toxicol. Environ. Health 32:49-57, 1991 3. Brown D, Lydon J, McLaughlin M, Stuart-Tilley A, Tyszkowski R, and Alper S, Histochem. Cell. Biol. 105:261-267, 1996.

cell morphology; epididymis; cadmium; rat

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