Caspases are associated with apoptosis in human ejaculated spermatozoa and in spermatogenesis

The spermatogenesis in human is controlled by apoptosis including externalization of phosphatidyl serine (PS) and activation of caspases (CP). It was the objective to detect CP by immunochemistry and by blotting technique in fresh and cryopreserved ejaculated spermatozoa and in testicular tissue. In spermatozoa the CP were investigated in relation to impairment of sperm plasma membrane which starts with the externalization of phosphatidylserine (PS) as one of the earliest signs of apoptosis. CP were found in ejaculated spermatozoa as well as in germinal epithelium of the testis. An activation of CP (aCP) was only detectable after externalization of PS at the sperm surface. Various germ cell nuclei of early phases of spermatogenesis and Sertoli cells of tissue samples with Sertoli-cell-only syndrome (SCO) showed CP3. The cryopreservation itself without impairment of sperm membrane did not activate CP. The Western blot (WB) demonstrated precursors of CP3, CP8 and CP9 and active forms of CP3 and CP9 in the ejaculated spermatozoa. The results suggest an important role of CP in controlling germ cell development and degradation.