Mitochondrial function in vitrified versus slow-frozen murine embryos

The effects of vitrification and slow-freezing on mitochondrial functions of in vitro produced murine embryos at various developmental stages were investigated using the Confocal Laser Scanning Microscope (CLSM). Oocytes were obtained from superovulated females, fertilized with sperm and cultured. Resulting 2-, 4- and 8-cell embryos were collected and cryopreserved by vitrification and slow-freezing. Mitochondria were stained with MitoTracker Red (CMXRos). Images were viewed by CLSM and analyzed using QWin SoftwareV.3. Fluorescent intensities were used to indicate viability. Results showed that mitochondrial fluorescence intensities of cryopreserved embryos were significantly lower as compared to non-cryopreserved embryos (p<0.01). Vitrification was found to be superior to slow-freezing at all developmental stages, based on mitochondrial function.