Low temperature preservation of rabbit embryos

Abstract

Rabbit embryos (4 cell, 8 cell and morulae) survived freezing and thawing in the presence of 1.5 (M) DMSO. Highest survival rates, assessed by continued development in vitro for 48 to 72 hr, were obtained with cooling rates of 0.74 to 0.90°C/min and thawing rates of 012 and 015°C/min (76%, 83%, 77% and 69% respectively). Transfer of embryos directly to liquid nitrogen after cooling at optimal rates to -110°C instead of -80°C significantly reduced the incidence of rupture of the zona pellucida and mucin coat and increased the rate of recovery. Viability after transfer was low (7% liveborn) and was not correlated with the higher rates of development in vitro to the morula and blastocyst stage.