title: Human sperm head vacuoles are physiological structures formed during the sperm development and maturation process.
abstract: OBJECTIVE
  To clarify whether human sperm vacuoles affected intracytoplasmic sperm injection (ICSI) success rates.
  
  
  METHODS
  Retrospective study.
  
  
  METHODS
  A private infertility clinic.
  
  
  METHODS
  Spermatozoa and spermatids were obtained from 11 normozoospermic, 10 oligozoospermic or asthenozoospermic, 4 obstructive azoospermic, and 3 nonobstructive azoospermic men.
  
  
  METHODS
  Differential interference contrast observation and intracytoplasmic injection of morphologically selected sperm.
  
  
  METHODS
  Incidence, size, and position of vacuoles of sperm cells were recorded. Ability of fertilization and blastocyst development were compared between cells with and without vacuoles.
  
  
  RESULTS
  More than 97.4% of ejaculated, 87.5% of epididymal, 87.5% of testicular spermatozoa, and more than 90.0% of Sc-Sd2 spermatids had vacuoles of various sizes. The incidence of vacuoles on ejaculated cells was significantly higher than that on the other types of cells, but there was no difference between sperm from normozoospermic men and those from the other donors. Removal of plasma membrane and/or acrosome did not affect the incidence of vacuoles. Although more than 60% of spermatozoa had small vacuoles in the acrosomal regions, 52.6% of Sb1-2 spermatids had large vacuoles. After injection of a motile spermatozoon with large and small vacuoles, 60.9% and 85.7% of metaphase II oocytes could be normally fertilized, respectively, and almost half of the zygotes developed to the blastocyst stage. When using sperm without vacuoles, the fertilization rate was 80.0%, but only 25% of them developed to the blastocyst stage.
  
  
  CONCLUSIONS
  Human sperm head vacuoles did not affect ICSI outcomes.
authors.affiliation: Saint Mother Obstetrics and Gynecology Clinic and Institute for Assisted Reproductive Technology, Fukuoka, Japan. incho@stmother.com
authors.forename: Atsushi
authors.initials: A
authors.lastname: Tanaka
authors.forename: Motoi
authors.initials: M
authors.lastname: Nagayoshi
authors.forename: Izumi
authors.initials: I
authors.lastname: Tanaka
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kusunoki
mesh_terms: D000328:Adult; D048429:Cell Size; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009865:Oocytes / Q000254:growth & development; D012189:Retrospective Studies; D013077:Sperm Head / Q000502:physiology*; D020554:Sperm Injections, Intracytoplasmic / Q000379:methods*; D013094:Spermatozoa / Q000254:growth & development; D014617:Vacuoles / Q000502:physiology*