RESUMO
Nowadays gamete and embryo freezing is an appropriate approach for preserving of genetic traits in laboratory animals, rare and endangered species. Frozen cells are suitable replace for actively breeding animals colony. The aim of this study was to preserve laboratory mouse embryo, using vitrification method and comparing effect of two cryoprotectants, glycerol sucrose [GS] and ethylene glycol-ficoll-sucrose [EFS40] on 8-cells and morula stage embryos of the mouse. Following mice superovulation 258[73.5%] out 351 embryos were in 8-cell and moroula stages. 188 morphologically intact embryos were exposed in the GS and EFS40 drops and then each 4 of them transferred to one special micro tube and after ends sealing, finally were cooled up to- 196[degree sign] C with liquid nitrogen vapors and immediately plunged into liquid nitrogen. One to three months later, embryos were thawed, recovered and cultured. The recovery rate of post-thawing embryos from EFS group [90%] was more than percentage of embryos recovered from GS [85%] group. In also survival rate of embryos undergoing further cleavage post-culturing to blastocyte stage, from EFS and GS groups were 53/7% and 19/6% respectively. This difference was significant at p<0.001. However difference between EFS group with fresh embryos, un-frozen embryos, for achieve to blastocytes stage which was 68/6% for second group, wasn't significant [p<0.05], but this item was significant between fresh embryo ang GS groups [p<0.001]. Generally results of our study show that, use of vitrification of 8-cell and morula NMRI mouse strain embryos using EFS as cryoprotectant is a suitable, easy and economical method for preservation of mouse embryos