title: The shape of the sperm midpiece in intracytoplasmic morphologically selected sperm injection relates sperm centrosomal function.
abstract: OBJECTIVE
  To evaluate whether the morphology of the sperm midpiece observed by high magnification microscopy relates to sperm centrosomal function.
  
  
  METHODS
  Sperm selected by conventional microscopy were defined as controls. By high magnification microscopy, sperm with straight midpieces were defined as Group 1, while those with tapering midpieces were defined as Group 2. Heterologous ICSI of human sperm into bovine oocytes was used to assess human sperm centrosomal function and analysis of sperm aster formation.
  
  
  RESULTS
  The total rate of sperm aster formation was 80.5% in Group 1, which was significantly higher (P < 0.05) than the rate of 33.3% seen for Group 2. Furthermore, sperm aster formation rates tended to be higher for Group 1 than for the controls.
  
  
  CONCLUSIONS
  This study demonstrates improvement of sperm aster formation rates by selecting sperm on the basis of midpiece morphology. The injection of selected sperm bearing morphologically straight midpieces may contribute to improved expression of sperm centrosomal function, providing a positive effect on fertilization after ICSI.
authors.affiliation: Department of Obstetrics and Gynecology, Tohoku University School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8574, Japan.
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Ugajin
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Terada
authors.forename: Hisataka
authors.initials: H
authors.lastname: Hasegawa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nabeshima
authors.forename: Kichiya
authors.initials: K
authors.lastname: Suzuki
authors.forename: Nobuo
authors.initials: N
authors.lastname: Yaegashi
mesh_terms: D000818:Animals; D002417:Cattle; D018385:Centrosome / Q000502:physiology*; D002843:Chromatin / Q000648:ultrastructure; D005260:Female; D006801:Humans; D008297:Male; D008846:Micromanipulation; D008853:Microscopy; D008854:Microscopy, Electron; D009865:Oocytes; D020554:Sperm Injections, Intracytoplasmic; D032961:Sperm Midpiece / Q000502:physiology / Q000648:ultrastructure*; D013084:Sperm-Ovum Interactions; D008941:Spindle Apparatus / Q000648:ultrastructure
chemical_list: D002843:Chromatin