The Fertility of Mice With Orthotopic Ovarian Grafts Derived From Frozen Tissue

Summary. Normal offspring were obtained from mice with orthotopic ovarian grafts of tissue that had been frozen and stored at —79° C. Tissue so treated showed a remarkable capacity for reorganization and function, but the number of oocytes surviving was small and the reproductive life of the females bearing the grafts was curtailed in each of the four strains of mice used. The most successful method of preservation involved soaking the tissue for 30 to 40 min in a medium consisting of 12% glycerol in horse serum before slow cooling to — 79° C. Oocyte destruction was increased when the concentration of glycerol was reduced to 8%, when the tissue was soaked for 1 to 2 hr in 15% glycerol in horse serum, and when the tissue was stored at —79° C for longer than 24 hr. Soaking in glycerol solutions at room temperature for 1½ hr without subsequent freezing also eliminated many oocytes. No viable grafts were obtained after `twostage' rapid cooling. Preservation of the fertility of mice with grafts of ovarian tissue has proved to be more difficult than maintenance of cyclic cornification of the vagina. The problems involved are discussed.