Use of chemically defined media for the vitrification of bovine oocytes

Most media used during oocyte vitrification contains protein sources of animal origin, which may raise epidemiological concerns, and as these compounds are not defined chemically, the outcome of vitrification may vary, as well. The aim of the study was to exclude proteins of animal origin from media and to replace it with chemically defined compounds. Prior to vitrification, the oocytes were pretreated with cholesterol loaded into methyl-beta-cyclodextrin or fetuin. After vitrification, the cholesterol treated group of oocytes resulted in higher cleavage rate and 8-cell-stage rate in comparison to the untreated oocytes or the ones vitrified with the traditional fetal calf serum containing media, but no effect was seen in their further development. The fetuin supplementation before vitrification did not result in any advantage, but the results were comparable to the standard process, during which fetal calf serum was used.