<em>In vitro</em> competence of vitrified bovine oocytes with open pulled straw

Abstract

<em>In vitro</em> developmental competences of post thaw vitrified bovine cumulus oocyte complexes (COCs) were studied. Good qualities COCs were cryopreserved using vitrification solution comprising of 15 or 20% ethylene glycol (EG) + 15% or 20% dimethyl sulfoxide (DMSO) + 0.6 M sucrose in tissue culture medium 199 (TCM199) with 10% fetal bovine serum (FBS). Immediately they were plunged in LN₂ for ultra- rapid freezing using open pulled straw. Thawing and dilution were made stepwise. Post thaw normal vitrified and non vitrified oocytes were subjected to <em>in vitro</em> maturation and fertilization. The performance in respect of post thaw survivality and <em>in vitro</em> maturation on the basis of cumulus cell expansion was more than 80%. In comparison, the non-vitrified COCs group, <em>in vitro</em> maturation performance was 93.12%. The <em>in vitro</em> fertilization performances of vitrified immature and mature post thaw oocytes were recorded as 50.65% and 56.16% with 17.95% and 19.51% of blastocysts formation, respectively. Ultra rapid freezing protocol using vitrification with open pulled straw technique i.e. 7.5 or 10% EG + 7.5 or 10% DMSO for equilibration at room temperature for 3 min and 15 or 20% EG + 15 or 20% DMSO + 0.6M sucrose as vitrification solution within 1 min, on immature bovine oocyte yielded acceptable <em>in vitro </em>oocyte growth and embryonic development.