title: Liquid nitrogen vapor is comparable to liquid nitrogen for storage of cryopreserved human sperm: evidence from the characteristics of post-thaw human sperm.
abstract: OBJECTIVE
  To compare the differences in the characteristics of post-thaw human sperm after storage in either liquid nitrogen (LN2; -196 °C) or LN2 vapor (-167 °C).
  
  
  METHODS
  Experimental study.
  
  
  METHODS
  University hospital.
  
  
  METHODS
  Thirty healthy volunteers who agreed to donate their normal semen samples for infertility or research were included in the study.
  
  
  METHODS
  Semen samples (n = 30) were divided into eight aliquots and frozen. Four aliquots of each human semen sample were stored in LN2 (-196 °C), and the other four aliquots were stored in LN2 vapor (-167 °C). After 1, 3, 6, or 12 months, samples were thawed and analyzed.
  
  
  METHODS
  The motility was evaluated by the manual counting method. The viability was estimated by eosin staining. The morphology was analyzed by Diff-Quik staining. The sperm DNA integrity was determined with acridine orange fluorescent staining, and acrosin activity was assayed by the modified Kennedy method.
  
  
  RESULTS
  The characteristics of post-thaw human sperm, including motility, viability, morphology, DNA integrity, and acrosin activity, showed no significant difference between LN2 and LN2 vapor storage for the different time periods.
  
  
  CONCLUSIONS
  LN2 vapor was comparable to LN2 in post-thaw sperm characteristics, suggesting that LN2 vapor may be substituted for LN2 for the long-term storage of human sperm.
authors.affiliation: Center for Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, People's Republic of China; National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Jinan, People's Republic of China; The Key Laboratory for Reproductive Endocrinology of Ministry of Education, Jinan, People's Republic of China; Shandong Provincial Key Laboratory of Reproductive Medicine, Jinan, People's Republic of China.
authors.forename: Jingmei
authors.initials: J
authors.lastname: Hu
authors.affiliation: Center for Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, People's Republic of China; National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Jinan, People's Republic of China; The Key Laboratory for Reproductive Endocrinology of Ministry of Education, Jinan, People's Republic of China; Shandong Provincial Key Laboratory of Reproductive Medicine, Jinan, People's Republic of China.
authors.forename: Shidou
authors.initials: S
authors.lastname: Zhao
authors.affiliation: Center for Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, People's Republic of China; National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Jinan, People's Republic of China; The Key Laboratory for Reproductive Endocrinology of Ministry of Education, Jinan, People's Republic of China; Shandong Provincial Key Laboratory of Reproductive Medicine, Jinan, People's Republic of China.
authors.forename: Chengyan
authors.initials: C
authors.lastname: Xu
authors.affiliation: Center for Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, People's Republic of China; National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Jinan, People's Republic of China; The Key Laboratory for Reproductive Endocrinology of Ministry of Education, Jinan, People's Republic of China; Shandong Provincial Key Laboratory of Reproductive Medicine, Jinan, People's Republic of China.
authors.forename: Lin
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Center for Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, People's Republic of China; National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Jinan, People's Republic of China; The Key Laboratory for Reproductive Endocrinology of Ministry of Education, Jinan, People's Republic of China; Shandong Provincial Key Laboratory of Reproductive Medicine, Jinan, People's Republic of China.
authors.forename: Shaoming
authors.initials: S
authors.lastname: Lu
authors.affiliation: Center for Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, People's Republic of China; National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Jinan, People's Republic of China; The Key Laboratory for Reproductive Endocrinology of Ministry of Education, Jinan, People's Republic of China; Shandong Provincial Key Laboratory of Reproductive Medicine, Jinan, People's Republic of China.
authors.forename: Linlin
authors.initials: L
authors.lastname: Cui
authors.affiliation: Center for Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, People's Republic of China; National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Jinan, People's Republic of China; The Key Laboratory for Reproductive Endocrinology of Ministry of Education, Jinan, People's Republic of China; Shandong Provincial Key Laboratory of Reproductive Medicine, Jinan, People's Republic of China. Electronic address: majinlong123@hotmail.com.
authors.forename: Jinlong
authors.initials: J
authors.lastname: Ma
authors.affiliation: Center for Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, People's Republic of China; National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Jinan, People's Republic of China; The Key Laboratory for Reproductive Endocrinology of Ministry of Education, Jinan, People's Republic of China; Shandong Provincial Key Laboratory of Reproductive Medicine, Jinan, People's Republic of China; Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics, Center for Reproductive Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People's Republic of China.
authors.forename: Zi-Jiang
authors.initials: ZJ
authors.lastname: Chen
mesh_terms: D000328:Adult; D048430:Cell Shape; D002470:Cell Survival; D003080:Cold Temperature / Q000009:adverse effects; D015925:Cryopreservation / Q000379:methods*; D004249:DNA Damage; D006785:Hospitals, University; D006801:Humans; D008297:Male; D009584:Nitrogen; D018570:Risk Assessment; D012662:Semen Preservation / Q000009:adverse effects / Q000379:methods*; D013076:Sperm Count; D013081:Sperm Motility; D013094:Spermatozoa / Q000473:pathology; D013997:Time Factors; D014835:Volatilization; D055815:Young Adult
chemical_list: D009584:Nitrogen
keywords: Storage; human sperm; liquid nitrogen; liquid nitrogen vapor