title: Cytogenetic effects of cryopreservation on human sperm: assessment using an improved method for analyzing human sperm chromosomes.
abstract: OBJECTIVE
  To evaluate any cytogenetic effects of cryopreservation on human sperm by comparing the frequencies of sperm chromosome anomalies and sex ratios before and after freezing.
  
  
  METHODS
  Using in vitro fertilization of zona-free hamster oocytes, analysis of sperm chromosomes was first performed on portions of fresh human semen samples. The residual semen was then analyzed for sperm chromosomes after cryopreservation for several weeks. Sperm donors were 5 healthy men aged 26-38 years.
  
  
  RESULTS
  A total of 166 sperm karyotypes were analyzed, 94 before freezing and 72 after freezing. The results indicated no significant differences between fresh and frozen sperm in either frequencies of aneuploidy (fresh: 0%, frozen: 2.8%) or structural anomalies (fresh: 7.5%, frozen: 9.7%). The sex ratios did not differ from the expected 1:1 ratio under either condition.
  
  
  CONCLUSIONS
  The results of these studies indicate that cryopreservation does not exert any cytogenetic mutagenicity on human spermatozoa or alter X/Y ratio of human sperm.
authors.affiliation: Department of Obstetrics and Gynecology, Nagoya City University of Medical School, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Okada
authors.forename: K
authors.initials: K
authors.lastname: Suzumori
authors.forename: Y
authors.initials: Y
authors.lastname: Yagami
mesh_terms: D000328:Adult; D000818:Animals; D002869:Chromosome Aberrations / Q000235:genetics*; D006224:Cricetinae; D015925:Cryopreservation; D005260:Female; D006801:Humans; D008297:Male; D008647:Mesocricetus; D012662:Semen Preservation / Q000009:adverse effects*