Laser zona drilling does not induce hsp70i transcription in blastomeres of eight-cell mouse embryos.

To assess whether zona drilling with a 1,480-nm laser induces heat shock in eight-cell embryos, we measured hsp70i RNA levels in sets of single blastomeres isolated after laser treatment of mouse embryos that had or had not been heated at 43 degrees C. Unlike heating, laser zona drilling did not stimulate hsp70i expression, even in the blastomeres closest to the laser beam, corroborating the safety of this procedure for assisted reproduction.