Thesis (M.Sc.) - Cairo University - Faculty of Agriculture - Department of Animal Production

Successful cryopreservation of oocytes would preserve the genetic material from superior animals. However, oocyte cryopreservation is relatively poor comparing to embryos and semen due to the extreme sensitivity to chilling. Therefore, the objective of this study was to determine the effect of vitrification process before and after oocyte maturation on the expression level of three quality related genes and on the nuclear and cytoplasmic maturation rates of vitrified immature buffalo oocytes. A total of 581 immature buffalo oocytes cumulus complex were collected and divided into five groups, Group 1 (fresh oocytes collected directly immature (IO)), group 2 (oocytes collected directly after subjecting to IVM (control)), Groups 3 (immature oocytes recovered morphologically normal after being subjected to vitrificatio (IOV)), group 4 (mature oocytes recovered morphologically normal after being subjected to vitrification then subjected to IVM (IV)), group 5 (mature oocyte recovered morphologically normal after being subjected to IVM then subjected to vitrification (MV)). Maturation rate was determined by cumulus cells expansion (cytoplasmic maturation) and by presence of first polar body (nuclear maturation). Vitrified-warmed buffalo oocytes were examined under an inverted microscope to assess the post-thaw morphological status. The mRNA expression analysis was performed to assess the expression of three quality related genes (SOD1, BAX and MAPK14)

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