Prepubertal and adult ovine oocytes show different sensitivity to vitrification procedures

The aim of our work was to assess the effect of cryoprotectants and vitrification 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.