VITRIFICAZIONE di oociti MII di cavallo mediante tecnica Minimal Essential Volume(cryotop)

In vitro matured horse oocytes were cryopreserved by vitrification using the Minima! Essential Volume Technique (MEMT) using as device the Cryotops. MII oocytes derived from expanded ( +) and compacted cumuls cells (-) were divided for the vitrification procedures as follow: A) Oocytes were exposed for 3' in TCM 199 + 20% FSC with 7.5% EG + 7.5% DMSO; 20-30 " in TCM 199 + 20% FSC + 16.5% EG + 16.5% DMSO + 0.5M saccarosio(V1); loaded with 2ul ofV1 on the cryotop and pluged directly in the liquid nitrogen; B) oocytes were incubated in TCM 199 + 20% FCS + 10% EG + 10% DMSO per 30"; 20" in TCM 199 + 20% FCS + 20% EG + 20% DMSO + 0.25 M Sucrose , loaded in the cryotop(2Jll) and pluged in the liquid nitrogen. Thawing was performed washing the oocytes in TCM 199 + 20% FCS with decreasing sucrose concentrations (1.25M, 0.62 M, 0.31 M). Surviving rate of the oocyte was no t statistically different in expanded and compacted oocytes and in A and B systems ranging between 40.9% and 57.1 %. After ICSI we observed lower fertilization rate in vitrified oocytes compared to the contro! group