TESTICULAR EFFECTS OF 1,3,5-TRINITROBENZENE (TNB) .2. IMMUNOLOCALIZATION OF GERM-CELLS USING PROLIFERATING CELL NUCLEAR ANTIGEN (PCNA) AS AN ENDOGENOUS MARKER

The applicability of PCNA as a tool for the analysis of germ cells in rats treated with 1,3,5-trinitrobenzene (TNB), a potent testicular tox icant, was evaluated. Male Fischer 344 (F344) rats were gavaged with T NB at 71 mg/kg or with corn oil (vehicle). Rats were killed after 10 d aily oral doses or were allowed to recover for 10 or 30 d after the 10 doses. Testes from control rats, treated rats, and rats allowed to re cover were immunohistochemically stained for PCNA. PCNA labeling in th e control rats was confined to the nuclei of spermatogonia, pachytene spermatocytes, and nuclei of elongate spermatocytes. Conventional (hem atoxylin and eosin) staining of testes from rats treated with TNB at 7 1 mg/kg for 10 d revealed loss of germ cells and cessation of spermato genesis. Immuno-histochemical staining of sections from these treated rats revealed only PCNA-positive spermatogonia. Rats allowed a 10-d re covery had both spermatogonial and spermatocytic staining, indicating partial restoration of germ-cell population. In rats allowed to recove r for 30 d, the PCNA staining pattern was identical to the control rat s. These results indicate that PCNA can be used to assess the prolifer ative status of spermatogonia (germ cells) in rodent testes exposed to testicular toxicants.