Testicular tissue from mature male Sprague-Dawley rats was maintained in culture at 33 degrees C or 37 degrees C. Detergent-extracted proteins were separated by polyacrylamide gel electrophoresis (PAGE) followed by staining or fluorography. Unilateral surgical cryptorchidism was performed as an in vivo model for testicular exposure to abdominal temperature. Testes were harvested at various time points, followed by protein analysis as performed for in vitro studies. Tissue incubated in vitro for 48 h at 37 degrees C demonstrated loss of a prominent actively synthesized 95 kD protein (p95) seen at 33 degrees C. No other temperature-dependent protein changes were observed. Liver, kidney, spleen and thymus failed to reveal p95 or any other temperature-sensitive proteins when incubated at 33 degrees C and 37 degrees C. Surgical cryptorchidism resulted in loss of p95 by 1 week in abdominal testes and normal p95 expression in sham-operated scrotal testes. p95 appears to be a temperature-sensitive protein in rat testis, with increased degradation accounting for its loss at abdominal temperature. The failure to identify similar protein changes in other tissues suggests a role for p95 in the temperature-dependent function of the testis.