Nylon mesh cryodevice for bovine mature oocytes, easily removable excess vitrification solution

Abstract The aim of this study was to determine pore size of nylon mesh (NM) device suitable for cryosurvival of bovine mature oocytes and to apply the device to vitrification of large quantities of the oocytes. Ten to twelve oocytes were loaded onto an NM device (a square opening 37-, 57- or 77-μm on a side length). After removal of the excess volume of vitrification solution by paper absorption, the oocytes were vitrified-warmed, fertilized and cultured in vitro. Oocyte recovery and morphological survival were comparable among the three groups. However, blastocyst yield in the 37-μm group (39%) was higher than that in the 77-μm group (28%), and the yield in the 57-μm group (31%) was the intermediate. The 37-μm NM device was applicable for increased oocyte number >40 (blastocyst yield, 33%). These results suggest that 37-μm-pore sized NM can serve as cryodevice to vitrify large quantities of in vitro-matured bovine oocytes.