Protective effect of sucrose on the survival of mouse and rat embryos stored at 0 degree C.

Mouse and rat embryos were stored at 0 degree C for 24-120 h in PBS containing sucrose. Higher proportions of mouse morulae developed into expanded blastocysts in culture when they were stored in 0.25, 0.5 or 0.75 M-sucrose than in 0, 0.1 or 1.0 M-sucrose. The greatest survival rates were obtained with 0.75 M-sucrose when examined after 48 (72%), 72 (62%) and 96 (41%) h of storage. No rat morulae developed after storage at 0 degree C for 24 h in PBS, but when 0.5 or 0.75 M-sucrose was added to the storage medium, 50-68% of embryos developed into blastocysts in culture, the proportions decreasing until they reached 15-21% after 120 h of storage. Mouse and rat embryos stored at 0 degree C for 3-4 days were transferred to recipients, and 2/2 mice and 1/2 rats delivered full-term young. When mouse embryos stored in 0.75 M-sucrose were frozen to -196 degrees C or when freshly collected frozen-thawed embryos were stored at 0 degree C, embryonic survival was improved when the embryos were incubated for 1-6 h between the two treatments.