Abstract: Objective To study the expression and regulation of heat shock protein 90β (HSP90β) in the testis, epididymis and
sperms of mice. Methods The localization and expression of HSP90β mRNA and protein were investigated in the testis,
epididymis and sperms of mice, and the regulation of HSP90β in the male reproductive system was explored. Results HSP90β
was expressed at a higher level in the epididymis than in the testis. In the sperms of the mice, HSP90β was localized in the
acrosome area. The expression of HSP90β in mouse epididymis decreased after castration and recovered the normal level after
testosterone treatment. HSP90β expression in the testis and epididymis also underwent changes during the postnatal
development of the mice. Conclusion HSP90β may play an important role in spermiogenesis and fertilization, and its
expression pattern in the epididymis after castration and during the postnatal development suggests its regulation by
hormones and development.