CRYOPRESERVATION OF SHEEP OOCYTES AND EMBRYOS USING LOCAL, MODIFIEID VITRIFICATION TOOL

Abstract

The present study was aimed to cryopreserve mature, immature oocytes and in vitro produced embryos in Iraqi sheep using vitrification technique by local, simple and cost effective vitrification tool. This tool is an innovative straw called vitripeace invented, designed and used for the first time. Immature oocytes were aspirated from ovaries of slaughtered ewes and subjected to in vitro maturation and in vitro fertilization programs.The immature, mature oocytes and embryos were vitrified using Vitripeace tools, then thawed and assessed for the morphology and viability. The results revealed non-significant effect of time on viability (%) and normal morphology (%) of vitrified immature and mature oocytes for post-thawing and 2 hours post-thawing. The results showed significant (P<0.05) reduction   in the viability (%) of 2 cell embryo namely 88.89% and 77.78 %  for post-thawing and two hours post-thawing respectively. The results revealed a significant (P<0.05) reduction on normal morphology of 1 cell embryo namely 88.24 % and 76.47 %  for post-thawing  and two hours post-thawing respectively. Significant (P<0.05) differences in the percentage of normal morphology were found at post-thawing period for all stages of embryo development which were 90.74%, 88.31, 88.24 and 83.33 for immature , mature oocytes, 1 cell and 2 cell embryos, respectively while no significant differences in the viability at post-thawing period among all stages of embryo development. It was concluded that, successful vitrification of oocytes and embryos was resulted using Vitripeace which was novel, simple and cost effective vitrification tool.