title: [Effects of 5 ml straws cryopreservation on the quality and ultrastructure of boar semen].
abstract: OBJECTIVE
  To investigate damages to the quality of boar sperm frozen in 5 ml straws, pellet and 0.25 ml straws as well as the ultrastructural changes of frozen boar sperm in 5 ml straws.
  
  
  METHODS
  We compared 3 different freezing packages of 5 ml straws, pellet and 0.25 ml straws to determine their effects on frozen boar semen, and observed the morphological and ultrastructural changes of the boar sperm in the 5 ml straws using scanning electron microscopy.
  
  
  RESULTS
  In the 5 ml straws, the vitality and motility of the boar sperm after freezing were not significantly different from those in the other two formulations, the normal apical ridge (NAR) was 52.65%, higher than in the pellet but not significantly different from that in the 0.25 ml straws, and the sperm membranes were mostly bubbly, some locally broken, which indicated the damage induced by freezing and thawing.
  
  
  CONCLUSIONS
  At the present time, boar semen frozen in 5 ml straws were not significantly different from those frozen in 0.25 ml straws. The existing freezing-thawing method may cause certain damage to the quality and ultrastructure of boar sperm, and therefore needs to be further improved.
authors.affiliation: Animal and Veterinary Research Institute, Shanghai Academy of Agricultural Science, Shanghai 201106, China. yinfangzhi@yahoo.com.cn
authors.forename: Fang-Zhi
authors.initials: FZ
authors.lastname: Yin
authors.forename: Jian-Jun
authors.initials: JJ
authors.lastname: Dai
authors.forename: Hua-Li
authors.initials: HL
authors.lastname: Wu
authors.forename: Cai-Feng
authors.initials: CF
authors.lastname: Wu
authors.forename: Ting-Yu
authors.initials: TY
authors.lastname: Zhang
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.forename: Shan-Ting
authors.initials: ST
authors.lastname: Yang
authors.forename: De-Fu
authors.initials: DF
authors.lastname: Zhang
mesh_terms: D000177:Acrosome / Q000648:ultrastructure*; D000818:Animals; D002462:Cell Membrane / Q000648:ultrastructure*; D015925:Cryopreservation / Q000379:methods*; D008297:Male; D008855:Microscopy, Electron, Scanning; D012662:Semen Preservation / Q000379:methods*; D013094:Spermatozoa / Q000648:ultrastructure*; D013552:Swine