Expression of heat shock proteins in developing and degenerating rat testes

In the testis, several types of heat shock proteins (HSPs) have been identi fied and characterized, although the cellular basis of the HSPs remains elu sive. In the present study, alterations in the cellular localization of HSP s, including HSP 25, 60, 70, and 90, were studied during the developing and degenerating periods in the rat testis using immunohistochemistry and West ern blotting. HSP25 was expressed in neither germ cells nor somatic cells o n all days examined. In contrast, HSP 60 was expressed in Leydig cells duri ng neonatal and prepuberty periods, and only in spermatogonia and primary s permatocytes after puberty. HSPs 70 and 90 were expressed in germ cells, Se rtoli cells, and Leydig cells during neonatal and early developing testes, and in spermatocytes and round spermatids after puberty. Besides, there was faint expression of HSP 90 protein in spermatogonia in this period. In the degenerative condition, all HSP proteins were markedly expressed in germ c ells after surgery. It would appear that HSPs play roles in unique homeosta sis in testes.