Effects of Scrotal Insulation and Pathological Lesions on .ALPHA.-Smooth Muscle Actin (SMA) and Vimentin in the Bull Testes

Abstract

The expression patterns of alpha-smooth muscle actin (SMA) and vimentin in the bovine testis indicate the maturation status of seminiferous tubules. The present study demonstrates the effects of impaired spermatogenesis resulting from increased testicular temperature after scrotal insulation and pathological lesions in subfertile bull testes on the changes in immunohistochemical expression of alpha-SMA and vimentin. Scrotal insulation induced degenerative changes of seminiferous tubules, and subfertile bull testes demonstrated characteristic mixed atrophied lesions; dysplastic lesions were seen in one bull. The increased intensity of peritubular alpha-SMA in the dysplastic area was distinct and indicated shrinkage of the seminiferous tubules. The mixed atrophied lesions revealed unaltered expression of peritubular alpha-SMA. However, considerable distortion was observed in the expression of alpha-SMA in severely degenerated tubules after insulation, which may indicate the heat sensitivity of peritubular alpha-SMA or its relation with spermatogenic activity under sudden heat stress. The vimentin expression pattern in the degenerated tubules of post-insulated testes was unaltered. However, the Sertoli cell-only tubules of mixed atrophied subfertile bull testes were characterized by an increase in vimentin of strong intensity resembling that in the transforming pattern, which may indicate the reversion of Sertoli cell maturity in such cases.