title: Effects of different laser-drilled openings in the zona pellucida on hatching of in vitro-produced cattle blastocysts.
abstract: OBJECTIVE
  To examine whether the size of artificial openings in the zona pellucida effects the hatching process in in vitro-produced cattle embryos.
  
  
  METHODS
  We evaluated the course of hatching of cattle blastocysts with and without laser-drilled zona pellucida openings of different sizes.
  
  
  METHODS
  University-based cattle reproductive biotechnology laboratory.
  
  
  METHODS
  Cattle blastocysts were produced in vitro. Laser treatment was performed 7 days after fertilization. In group I, a small opening of 7-15 microm in width and 40 microm in length was created. In group II, an opening of at least 40 by 40 microm was created. Group III blastocysts received no laser treatment.
  
  
  METHODS
  Hatching course, zona pellucida thickness, diameter.
  
  
  RESULTS
  By day 9, the rate of hatched blastocysts was 27.1%, 63,0%, and 42,9% in groups I, II, and III, respectively. The remainder in group I were entrapped during hatching in a typical figure eight shape. The hatching rate in group II was significantly different from the other groups. All laser-treated blastocysts (groups I and II) showed no change of zona pellucida diameter until day 9.
  
  
  CONCLUSIONS
  These results suggest that the size of the artificial openings in the zona pellucida has an influence on the hatching process.
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000502:physiology*; D002417:Cattle; D010064:Embryo Implantation / Q000502:physiology*; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods / Q000662:veterinary*; D053685:Laser Therapy; D008297:Male; D008846:Micromanipulation / Q000379:methods; D011247:Pregnancy; D011897:Random Allocation; D015044:Zona Pellucida / Q000502:physiology*