Low-temperature cryopreservation of BB rat embryos of spontaneously diabetic rats

Cryopreservation of BB rat embryos would ensure perpetuation, at greatly reduced cost, of this model of nonobese, insulin-dependent, juvenile-onset diabetes in man. Immature prediabetic female BB rats were ovulated hormonally. The embryos were removed at the 8- to 16 cell and blastocyst stages and cryopreserved, and after thawing were assayed for viability in vitro or transplanted into pseudopregnant foster mothers of a nondiabetic strain. The highest rate of viability in vitro (100%) and development into normal fetuses (31%) was obtained with blastocysts transplanted into day-4 foster mothers. The results indicate the feasibility of low-temperature banking of this clinically important strain of rats.