effect of various concentrations of minimal essential medium vitamins (mem vitamins) on development of sheep oocytes during in-vitro maturation

abstract background: improvements in culture media formulations have led to an increase in the ability of sheep embryo in culture throughout the preimplantation period. objective: this study was carried out to evaluate the effects of various concentrations of mem vitamins during in vitro maturation of sheep oocytes and subsequent embryo development. materials and methods: sheep ovaries were collected from a slaughterhouse and transported to the laboratory. oocytes were matured in sof medium supplemented with, ecg, hcg and egf in various concentrations of mem vitamins (control, 0.5, 1 and 1.5 ) for 24h. the cumulus oocyte compelex (cocs) were co-incubated with epididymal spermatozoa of post mortem rams in synthetic oviduct fluid fertilization (soff) medium with 10% heat inactivated estrous sheep serum for 18h. embryos were cultured in synthetic oviduct fluid culture 1 (sofc1) medium for 48h followed by cultured in synthetic oviduct fluid culture 2 (sofc2) medium for six days. results: addition of 0.5 and 1 mem vitamins significantly increased (p< 0.05) overall blastocyst development (21.62% and 22.33%; respectively) compared with 1.5 mem vitamins (15.59%), but there was no difference between control, 0.5 and 1 mem vitamins in the percentage of embryos successfully developing to the blastocyst stage (19.50%, 21.62% and 22.33% respectively). conclusion: it seems that addition of 1.5 of mem vitamins has detrimental effect on blastocyst rate.