Sucrose ‘Versus’ Trehalose Cryoprotectant Modification in Oocyte Vitrification : A Study of Embryo Development

Abstract

Numerous studies reported that vitrification, an ultra-rapid cooling technique, seems to be highly effective and could increase oocyte survival rate rather than slow freezing. The successful of oocyte vitrification depends on the proper combination of type and concentration of cryoprotectant. This study was addressed to determine the effects of the combination of type and concentration of cryoprotectants of vitrification media, notably in the embryo development. This experimental research was conducted by using oocyte obtained from thirty-two adult female Deutschland, Denken and Yoken (DDY) mice (7-8 weeks old). The MII mice oocytes were vitrified within 24 h after retrieval using the Cryotop method with cryoprotectants as follow : sucrose (16.5% EG, 16.5% DMSO, 0.5 mol/l sucrose), trehalose (16.5% EG, 16.5% DMSO, 0.5 mol/l trehalose) and Kitazato. The embryo development and morphological grading was observed at 2-cell and 8-cells under reverse phase light microscope and inverted microscope. This study demonstrated a good embryo development and morphological grading in sucrose and trehalose vitrification media. In embryo development, trehalose medium seems more superior compared to sucrose medium, even though Kitazato was the most superior compared to both. In the morphological grading, in 2-cells embryo, there were no significant differences between the three cryoprotectants, While, in 8-cells embryo, trehalose medium appeared to be superior compared to sucrose medium, even though seemed more inferior compared to Kitazato. The appropriate type and concentration of sugar as extracellular cryoprotectant was trehalose in oocyte vitrification based on embryo development, compared to sucrose.