Cryopreservation of Mouse Strains by Ultrarapid Freezing

Abstract

Two-cell mouse embryos from four different inbred strains (BALB/c, C3H/He, C57BL/6 and DBA/2) and one closed colony (Slc: ICR) were frozen by direct placement into liquid nitrogen after a 10-15 sec exposure to a highly concentrated solution (DAP 213: 2 M dimethyl sulphoxde, 1 M asetamide, 3 M propylene glycol in PB 1), and later thawed in a 37°C waterbath. The percentages of morphologically normal embryos were 80.7-92.6% on thawing. Morphologically normal embryos were then transferrd to the oviducts of peudopregnant recepients, and 7.4-60.0% of the embryos developed into normal young (BALB/c ; 34.3%, C3H/He ; 30.6%, C57BL/ 6 ; 60.0%, DBA/2 ; 7.4%, and Slc : ICR ; 24.3%) .