Frequency and Patterns of Premature Sperm Chromosome Condensation in Oocytes Failing to Fertilize After Intracytoplasmic Sperm Injection

Purpose: The purpose of this study was to evaluate reasonsfor fertilization failure after intracytoplasmic sperminjection as a part of internal quality control and to reviewcorresponding previous data.Methods: One hundred injected but unfertilized oocytes werefixed and examined after Giemsa staining.Results: Three oocytes (3.0%) did not show the presenceof a spermatozoon and two (2.0%) contained pronuclearstructures. An intact spermatozoon was found in 25 cases(25.0%), whereas the sperm nucleus had undergonepremature chromosome condensation (PCC) in 70 cells (70.0%).A modified classification system was established tocharacterize the different PCC patterns.Conclusions: PCC indicates a correct intracytoplasmicinjection and excludes technical problems as a major reasonfor fertilization failure in the present study. A lack of oocyteactivation due to cytoplasmic immaturity is consideredresponsible for the occurrence of PCC. A review of theliterature shows that the role of sperm chromatinabnormalities in the process of nuclear decondensation needs furtherinvestigation.