title: Effects of partial or complete laser-assisted hatching on the hatching of mouse blastocysts and their cell numbers.
abstract: BACKGROUND
  It is still debatable whether a full-thickness assisted hatching (AH) is better than the partial zona thinning. In this research, we used a mouse model to study the effect of partial and complete laser-AH on the rate of completely hatched blastocyst and their cell numbers.
  
  
  METHODS
  In experiment 1, mouse morulae had 0, 1, 2 or 3 full-thickness openings of 10 microns created in the zona pellucida with an infrared laser beam. In the second experiment, 0, 1 and 2 openings of 20 microns were studied. In the third experiment, a full-thickness opening of 20 microns or quarter-thinning of the zonal circumference to a depth of 90% was compared with non-AH controls.
  
  
  RESULTS
  No difference in blastocyst formation was found in laser-treated groups and in the controls. In experiment 1, the rate of completely hatched blastocysts was significantly lower than the controls. In experiment 2 when the size of the opening was increased, blastocysts completely hatched at a significantly higher rate than that in the controls. In experiment 3, the rate of completely hatched blastocysts was the highest in the full-thickness group. Cell numbers in completely hatched blastocysts from both AH groups were significantly fewer than those in the controls.
  
  
  CONCLUSIONS
  Full-thickness opening resulted in a higher rate of completely hatched blastocysts than quarter zonal-thinning and controls, but the cell numbers were significantly decreased.
authors.affiliation: Division of Reproductive Medicine, Department of Obstetric and Gynecology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand.
authors.forename: Chanchai
authors.initials: C
authors.lastname: Chailert
authors.forename: Usanee
authors.initials: U
authors.lastname: Sanmee
authors.forename: Waraporn
authors.initials: W
authors.lastname: Piromlertamorn
authors.forename: Sudarat
authors.initials: S
authors.lastname: Samchimchom
authors.forename: Teraporn
authors.initials: T
authors.lastname: Vutyavanich
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000166:cytology / Q000502:physiology / Q000648:ultrastructure; D046149:Embryo Culture Techniques; D047108:Embryonic Development; D005260:Female; D007834:Lasers; D051379:Mice; D008813:Mice, Inbred ICR; D008846:Micromanipulation; D009028:Morula; D015044:Zona Pellucida / Q000648:ultrastructure