Prepubertal and adult ovine oocytes show different sensitivity to vitrification procedures

The aim of our work was to assess the effect of cryoprotectants and vitri- fication procedures on prepubertal ovine oocytes. Prepubertal and adult COCs were matured in vitro and exposed to cryoprotectants (EXP) or vitrified/warmed (VIT) using the cryoloop as cryodevice. After treatment, we evaluated in vitro the viability and development and chromatin alterations. Prepubertal and adult oocytes did not differ (p > 0.05) in degeneration and cleavage rates both in EXP and VIT groups. In the EXP group, prepubertal blastocyst output was lower (p < 0.05) than in the adults, while it did not differ in VIT group. Chromatin alterations were more evident in prepubertal than in adult oocytes both in EXP and VIT groups (p < 0.01). In conclusion, prepubertal ovine oocytes show a high sensitivity to vitrification procedures and their use for cryobanking require more studies.