title: Frequency and patterns of premature sperm chromosome condensation in oocytes failing to fertilize after intracytoplasmic sperm injection.
abstract: OBJECTIVE
  The purpose of this study was to evaluate reasons for fertilization failure after intracytoplasmic sperm injection as a part of internal quality control and to review corresponding previous data.
  
  
  METHODS
  One hundred injected but unfertilized oocytes were fixed and examined after Giemsa staining.
  
  
  RESULTS
  Three oocytes (3.0%) did not show the presence of a spermatozoon and two (2.0%) contained pronuclear structures. An intact spermatozoon was found in 25 cases (25.0%), whereas the sperm nucleus had undergone premature chromosome condensation (PCC) in 70 cells (70.0%). A modified classification system was established to characterize the different PCC patterns.
  
  
  CONCLUSIONS
  PCC indicates a correct intracytoplasmic injection and excludes technical problems as a major reason for fertilization failure in the present study. A lack of oocyte activation due to cytoplasmic immaturity is considered responsible for the occurrence of PCC. A review of the literature shows that the role of sperm chromatin abnormalities in the process of nuclear decondensation needs further investigation.
authors.affiliation: Department of Gynecology and Obstetrics, University of Ulm, Donau, Germany.
authors.forename: B E
authors.initials: BE
authors.lastname: Rosenbusch
mesh_terms: D000328:Adult; D002467:Cell Nucleus / Q000473:pathology; D002843:Chromatin / Q000378:metabolism; D002869:Chromosome Aberrations; D005260:Female; D005306:Fertilization; D006651:Histocytochemistry; D006801:Humans; D007246:Infertility / Q000209:etiology / Q000473:pathology*; D008297:Male; D009865:Oocytes / Q000502:physiology*; D011786:Quality Control; D020554:Sperm Injections, Intracytoplasmic / Q000592:standards; D013094:Spermatozoa / Q000378:metabolism / Q000473:pathology*
chemical_list: D002843:Chromatin