A mouse geneticist's impatient waiting for the arrival of embryo-freezing techniques

Four cases from the author's own experience are discussed where the freezing and freeze-storage of mouse embryos would have saved much research time, preserved valuable genetic material, and enabled important genetic studies to have been made. These cases illustrate the problems encountered when transporting a large collection of inbred mouse strains; the necessity to discontinue--because of lack of space--strains that nobody wants at the moment but that might become invaluable in the future; the unavoidable loss of parental stocks used for the development of a new congenic line; and the difficulties one faces when studying a genetic system that is extremely polymorphic. The need for a centralized and possibly international embryo freezing and storing facility is advocated.