Isthmic and ampullary fluid enhance fertilization and cleavage rate of cow oocytes in vitro

Abstract

The aim of the work was to determine the susceptibility of non-cultured and cultured rabbit embryos at different stages of development to the adverse effects of vitrification. The experiment was carried out on non-cultured embryos at the 8- to 16-cell, morula and blastocyst stages, and on embryos collected at the 2-cell stage and cultured for 24, 48 or 72 h. The embryos were cultured in Menezo's B2 medium supplemented with 20% FCS (fetal calf serum), or were cocultured with oviductal epithelium cells. A mixture of 35% glycerol + 35% 1,2-propanediol in serum-supplemented, phosphatebuffered saline was used as a vitrification medium. The embryos were vitrified in glass ampoules or plastic straws. Dilution after rapid thawing was done in one step, in a 1 M sucrose solution.After vitrification of non-cultured embryos in glass ampoules, the survival rates of the 8- to 16-cell, morula and blastocyst stages were 55.9%, 88.4% and 83.1%, respectively.The survival rates of embryos derived from cultures of 2-cell embryos in Menezo's B2 medium for 24 h (8- to 16-cell stage), 48 h (morula stage) and 72 h (blastocyst stage) and then vitrified in glass ampoules were 46.7%, 62.4% and 36.2%, respectively. The percentage of live foetuses remaining 28 days after the transfer of 103 vitrified and 115 cultured and vitrified 8- to 16-cell embryos was 21.4% and 1.8%, respectively. After the transfer of 111 vitrified morulae and 112 cultured and vitrified morulae, the percentage of live foetuses 28 days later was 11.7% and 7.1%, respectively.After vitrification in plastic straws, the survival rates in vitro of non-cultured morulae, and of morulae resulting from the culture of 2-cell embryos for 48 h in Menezo's B2 medium and in the coculture system were 89.1%, 93.8% and 91.2%, respectively.