Vitrification of Canine Oocytes

The objective of the present study was to compare the vitrification method for cryopreservation of canine oocytes. Canine cumulus-oocyte complexes (COCs) were collected from ovaries, and were vitrified by ethylene glycol based (E30S) or DMSO based (DAP213) methods. In the E30S method, COCs were exposed to the vitrification solution, composed of 30% ethylene glycol and 0.5 M sucrose, step-wise transferred onto a cryotop holder, then plunged directly into liquid nitrogen. In the DAP213 method, COCs were exposed to 1 M DMSO and DAP213 solution in a cryotube, and thereafter plunged directly into liquid nitrogen. Although vitrified-warmed COCs in the E30S method showed fewer morphological abnormalities, and higher viability than those in the DAP213 method, there was no significant difference in between. These results indicate that either method of vitrification is available and statistically comparable for cryopreservation of canine oocytes.