Effects of in utero exposure to nonsteroidal estrogens on mouse testis.

Male mice exposed in utero to alpha-zearalanol (zeranol) or diethylstilbestrol (DES) were analyzed postnatally to evaluate the possible changes on their testicular morphology as part of an examination of the effects of transplacental exposure to non-steroidal estrogens on sensitive tissues. Pregnant NMRI mice were injected subcutaneously with ethyl oleate (0.1 mL) alone (negative control) or with 150 micrograms/kg of body weight of zeranol or DES (positive control) on days 9 and 10 of gestation. Experimental and control male offspring were euthanized at days 45 (n = 47), 90 (n = 44), 180 (n = 40) and 365 (n = 26) after birth and their gonads were examined by light and electron microscopy. The results suggested that prenatal zeranol or DES exposure induced more severe and earlier (at 45 d) testicular abnormalities than in negative control (at 6 mo). These age-related alterations were characterized by regressive changes in the germinal epithelium and Sertoli's cells as well as foci of Leydig's cells around atrophied seminiferous tubules and dysplasia of the rete testis epithelium. On the contrary, the presence of Leydig's cells with immature morphology and their arrangement in sheet could be attributable exclusively to estrogen treatment. The presence of no neoplasm was confirmed.