RESUMEN
Compacted mouse morulae were frozen at 0.3§C/min. or 0.5§C/min. from -6§C to -24§C or -32§C in 10 por cento of glycerol plus different sucrose concentrations with or without 0.1 por cento of honeybee royal jelly. Embryos were thawed in water bath at 22§C for 20 seconds and cryoprotectant dilution was done in three steps. Embryos were cultured in Whitten's medium for 24, 48 and 72 hours at 37§C, 5 por cento of CO2 and 100por cento of humidity. The in vitro development ranged from 56.6 por cento to 100 por cento after 72 hours. Expanded blastocysts were transferred to pseudopregnant recipients on the third day of the estrous cycle. Viable fetuses rates for embryos frozen to -24 or -32§C at 0.3§C/minute in 10 por cento glycerol + 10 por cento sucrose, 10 por cento glycerol + 10 por cento sucrose + 0.1 por cento honeybee royal jelly, 10 por cento glycerol + 0.1 por cento honeybee royal jelly or 10 por cento glycerol were respectively: 28.1 por cento and 13.6 por cento, 48.7 por cento and 31.9 por cento, 28.6 por cento and 13.2 por cento, 20.0 por cento and 42.4 por cento. Viable fetuses for embryos frozen to -24§C or -32§C at 0.5§C/minute in 10 por cento glycerol + 10 por cento sucrose or 10 por cento glycerol + 10 por cento sucrose + 0.1 por cento honeybee royal jelly were respectively 29.0 por cento and 15.3 por cento, 48.8 por cento and 32.0 por cento. We can conclude that addition of 10 por cento sucrose to 10 por cento glycerol was efficient for embryo freezing at 0.3 or 0.5§C/minute and plunged in liquid nitrogen at -24§C. The honeybee royal jelly addition provided higher viable fetuses rates when embryos were cooled at 0.3 or 0.5§C/minute and plunged in liquid nitrogen at -24§C