Cryotop vitrification of oocytes in a rabbit (Oryctolagus cuniculus) model. A study of viability of germinal cells at different post-mortem times

The vitrification of gametes represents a valid tool for safeguarding the genetic resources of wild endangered species. Aim of this study was to test a method to cryopreserve rabbit oocytes to identify a procedure applicable to cryopreservation of Italian hare (Lepus corsicanus) oocytes. Oocytes were collected by slicing of the ovaries (n = 80) of rabbits within 24, 48, 72 h post-mortem, denuded in Hepes-buffered TCM 199 (H199) added by 10% fetal calf serum (FCS) (Cai et al, 2005), vitrified by cryotop and afterwards warmed. Finally, their viability after the chilling injuries was evaluated by a dye-exclusion test using Trypan Blue. Post warming viability of vitrified oocytes decreased linearly from 0 to 72 h post mortem.The results obtained may be transferred to Italian hare, as it is considered as a “vulnerable” species, to bank its genetic value, allowing storage of oocytes at liquid nitrogen temperatures to be subsequently devoted to in vitro fertilization (IVF)