title: Birefringence characteristics in sperm heads allow for the selection of reacted spermatozoa for intracytoplasmic sperm injection.
abstract: OBJECTIVE
  To verify clinical outcome after injection of spermatozoa that have undergone the acrosome reaction (reacted spermatozoa) vs. those still having an intact acrosome (nonreacted spermatozoa).
  
  
  METHODS
  Prospective, randomized study.
  
  
  METHODS
  Reproductive Medicine Unit, Italian Society for the Study of Reproductive Medicine, Bologna, Italy.
  
  
  METHODS
  According to a prospective randomization including 71 couples with severe male factor infertility, intracytoplasmic sperm injection (ICSI) was performed under polarized light that permitted analysis of the pattern of birefringence in the sperm head. Twenty-three patients had their oocytes injected with reacted spermatozoa, 26 patient's oocytes were injected with nonreacted spermatozoa, and in 22 patients both reacted and nonreacted spermatozoa were injected.
  
  
  METHODS
  Intracytoplasmic sperm injection was performed under polarized light to selectively inject acrosome-reacted and acrosome-nonreacted spermatozoa.
  
  
  METHODS
  Rates of fertilization, cleavage, pregnancy, implantation, and ongoing implantation.
  
  
  RESULTS
  There was no effect on the fertilizing capacity and embryo development of either type of sperm, whereas the implantation rate was higher in oocytes injected with reacted spermatozoa (39.0%) vs. those injected with nonreacted spermatozoa (8.6%). The implantation rate was 24.4% in the group injected with both reacted and nonreacted spermatozoa. The delivery rate per cycle followed the same trend.
  
  
  CONCLUSIONS
  Spermatozoa that have undergone the acrosome reaction seem to be more prone to supporting the development of viable ICSI embryos.
authors.affiliation: Reproductive Medicine Unit, Italian Society for the Study of Reproductive Medicine, Via Mazzini 12, 40128 Bologna, Italy. luca.gianaroli@sismer.it
authors.forename: Luca
authors.initials: L
authors.lastname: Gianaroli
authors.forename: M Cristina
authors.initials: MC
authors.lastname: Magli
authors.forename: Anna P
authors.initials: AP
authors.lastname: Ferraretti
authors.forename: Andor
authors.initials: A
authors.lastname: Crippa
authors.forename: Michela
authors.initials: M
authors.lastname: Lappi
authors.forename: Serena
authors.initials: S
authors.lastname: Capitani
authors.forename: Baccio
authors.initials: B
authors.lastname: Baccetti
mesh_terms: D020101:Acrosome Reaction / Q000502:physiology*; D000328:Adult; D053627:Asthenozoospermia / Q000503:physiopathology / Q000628:therapy; D001718:Birefringence; D002469:Cell Separation / Q000379:methods; D010064:Embryo Implantation; D005260:Female; D005306:Fertilization; D006801:Humans; D007248:Infertility, Male / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D008859:Microscopy, Polarization; D011247:Pregnancy; D011256:Pregnancy Outcome; D011446:Prospective Studies; D013077:Sperm Head / Q000502:physiology*; D020554:Sperm Injections, Intracytoplasmic / Q000379:methods*; D013094:Spermatozoa / Q000502:physiology / Q000648:ultrastructure