title: Laser zona pellucida thinning--an alternative approach to assisted hatching.
abstract: BACKGROUND
  The purpose of this study was to assess the efficacy and hatching characteristics of in-vitro cultured human embryos subjected to laser zona pellucida thinning.
  
  
  METHODS
  Zona thinning was performed on 110 embryos using a non-contact 1.48 microm diode laser and the hatch rate in vitro was compared with 42 control embryos. Variation of zona thickness and degree of zona expansion was assessed. Scanning electron microscopy was performed on embryos entrapped during hatching to identify the site of hatching.
  
  
  RESULTS
  The rate of hatching was significantly higher in laser thinned blastocysts compared with control embryos (68 versus 33% respectively, P < 0.01). Laser thinning increased the variation of zona thickness in embryos from 11.6-27.3%. Natural zona thinning occurred in 92% of laser thinned hatching blastocysts and 100% of control embryos.
  
  
  CONCLUSIONS
  These results suggest that laser zona thinning is effective and may provide significant advantages over conventional assisted hatching techniques, which create holes.
authors.affiliation: Fertilitetscentrum, Carlander's Hospital, Göteborg, Sweden. debbie.blake@aut.ac.nz
authors.forename: D A
authors.initials: DA
authors.lastname: Blake
authors.forename: A S
authors.initials: AS
authors.lastname: Forsberg
authors.forename: B R
authors.initials: BR
authors.lastname: Johansson
authors.forename: M
authors.initials: M
authors.lastname: Wikland
mesh_terms: D046508:Culture Techniques; D004622:Embryo, Mammalian / Q000502:physiology / Q000648:ultrastructure; D006801:Humans; D007834:Lasers; D008846:Micromanipulation; D008855:Microscopy, Electron, Scanning; D012016:Reference Values; D012099:Reproductive Techniques; D015044:Zona Pellucida / Q000528:radiation effects*