Direct rehydration of in vitro fertilised bovine embryos after vitrification

Abstract

VITRIFICATION is a valuable embryo freezing technique because it is simple, quick, economic (Rall and Fahy 1985), reli­ able and reasonably easy to apply under field conditions (Niemann 1991). Vitrification offers considerable promise for simplifying and improving the cryopreservation of cells because controlled-rate freezing equipment is not required and the poten­ tial injury associated with the fonnation of ice is eliminated (Rail 1987). Tbe first successful vitrification of bovine embryos was achieved by Massip and others (1986). The survival of vitrified embryos is influenced by the type of cryoprotectant used and the exposure procedures (Yang and others 1992). Leibo (1989) suggested that embryos can be successfully vitrified in either glyc­ erol-based or propylene glycol-based solutions. Sucrose and other carbohydrates like trehalose are effective in preserving the.s c­ tural and functional integrity of membranes at low water activities (Massip and others 1987). Compact morulae seem to be the most suitable stage for vitrification, and the survival rate of expanded blastocysts can be increased up to 10-fold by using Massip solu­ tion and by equilibration of 4oC (Cseh and others 1992).