Efecto de la vitrificación sobre la viabilidad morfológica de embriones murinos ( Mus musculus )

The objective of present study was to evaluate the morphological viability post vitrification of murine embryos ( Mus musculus ) of two stages (morulae and blastocyst), obtained in vivo from superovulated female, following this criterion: morphologically intact blastomeres, intact zona pellucida, and re-expanding of the blastocele. Five hundred seventy two murine embryos of excellent quality were vitrified through the modified open pulled straw procedure, using an equilibrated solution (25% of ethylene glycol, 25% of glycerol) in three steps. There were not significant differences (P>0.05), between recovery rates for morula (92.6%) and blastocyst stage (93.7%). Nevertheless, we observed differences (P<0.05) for post vitrification morphological viability, being higher the number of blastocysts with normal morphological appearance (93.3%) compared to the number of morulae (87.5%). Six types of morphological abnormalities were observed: loss of spherical shape, partial absence and fracture of the zona pellucida, presence of extruded blastomeres, partial degeneration of the cellular mass, and total degeneration of blastomeres. Also differences in post vitrification damage were observed; only 6.7% of the blastocysts versus 12.5% of morulae had damage. These results represent the first experience of the vitrification technique in mammal embryos in Venezuela, suggesting that blastocysts tolerate the vitrification process more than morulae, because a higher viability and lower frequency of morphological abnormalities than morulae.El objetivo del presente estudio fue evaluar la viabilidad morfológica post vitrificación de embriones murinos ( Mus musculus ), de dos estadios de desarrollo (mórula y blastocito), obtenidos in vivo de hembras superovuladas, para lo cual se utilizaron los siguientes criterios: blastómeras morfológicamente intactas, zona pelúcida íntegra y re–expansión del blastocele. Quinientos setenta y dos embriones murinos de excelente calidad se vitrificaron a través de la técnica pajuela estirada abierta modificada, utilizando una solución de equilibración (25% de etilenglicol, 25% de glicerol) en tres pasos. No hubo diferencia significativa (P>0,05), entre la tasa de recuperación para mórulas (92,6%) y blastocitos (93,7%). Sin embargo, se obtuvo diferencia (P