The pesticide methoxychlor given orally during the perinatal/juvenile period, reduced the spermatogenic potential of males as adults by reducing their Sertoli cell number

Perinatal and juvenile oral treatment of rats with the insecticide, methoxychlor (MXC), reduced testicular size and other reproductive indices including the number of epididymal sperma- tozoa in those animals as adults (6). The objective was to determine if these males exposed during development had fewer Sertoli cells which might explain these testicular effects. Rat dams were gavaged with MXC at 0, 5, 50, or 150 mg.kg -1.day -1 for the week before and after they gave birth. Resulting male pups (15/group) then were dosed directly from postnatal day 7 to 42. Testes were fixed in Bouin's and in OsO4, embedded in Epon and sectioned at 0.5 μm, stained with toluidine blue, and evaluated stereologically or cut at 20 μm to measure Sertoli cell nuclei with Nomarski optics. Sertoli cell number was calculated as the volume density of the nucleus times the parenchymal weight (90% of testicular weight) divided by the volume of a single Sertoli cell nucleus. Across dose groups, there were no changes in the nuclear volume density, the volume of a single nucleus, or the number of Sertoli cells per g parenchyma. There were highly significant dose-related changes in the vol- ume of Sertoli cell nuclei per testis and the number of Sertoli cells per testis. Reduced testicular weight (r = 0.94) and reduced numbers of epididymal spermatozoa (r = 0.43) were significantly (p < 0.01) correlated to reduced number of Sertoli cells per testis. Hence, perinatal and juvenile oral exposure to MXC can reduce spermatogenic potential of males as adults by reducing their number of Sertoli cells.