ABSTRACT
The primary interest of our laboratory has been the development of objective biochemical markers of human sperm maturity and function, which would predict male fertility independently from the traditional semen criteria of sperm concentration and motility. In measurements of sperm creatine-N-phosphotransferase or creatine kinase
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(CK), we found significantly higher sperm CK contents in men with diminished fertility1,2. The sperm CK immunostaining patterns indicated (Figure 30.1a) that the high sperm CK activity was a direct consequence of increased cytoplasmic protein and CK concentrations in the spermatozoon3. This suggested that we had identified a sperm developmental defect in the last phase of spermiogenesis when the surplus cytoplasm (unnecessary for mature sperm) is normally extruded and left in the adluminal area as ‘residual bodies’4.
