Effect of different culture techniques used to induce capacitation on the chromatin stability of human sperm

To validate an in-vitro bioassay for assessing chromatin stability of human sperm, 38 semen samples from infertile men were studied using sodium dodecyl sulphate, an anionic detergent which disorganizes only the cytoplasmic membrane. Assay sensitivity was 50 sperm, whilst the within- and between-assay variation, and the between-observer variation were found to be within the accepted range for this type of bioassay. The influence of different in-vitro treatments currently used in some clinical assisted fertilization programmes was evaluated: a destabilizing effect occurred in Grade I (stable) and Grade III (swollen) sperm. In the former, all treatments reduced stable sperm; in the latter, a significant (P less than 0.001) increase in swollen sperm was shown with two methods that used Ham's F-10 as culture medium. Different chromatin patterns found in the treated sperm suggest the possibility that the recovered samples could be modified compared to their status at the time of isolation.