Vitrification of large quantities of immature bovine oocytes using nylon mesh.

Vitrification of oocytes and embryos has recently been improved using new physical supports such as electron microscope (EM) grids, open-pulled straws, and cryoloops. However, the number of samples per container was restricted in each of these methods. In the present study, to develop a novel simple technique for vitrification of large quantities of oocytes or embryos, we examined vitrification of large quantities of immature bovine oocytes using nylon mesh as a novel container. As many as 65 oocyte-cumulus cell complexes could be placed on nylon mesh for vitrification compared with 15 per EM grid. Recovery rates were higher when using nylon mesh than EM grids, while fertilization and development rates were not different. These results indicated that vitrification using nylon mesh is useful and offers a new way to cryopreserve large numbers of oocytes.