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Articles by M. Dashtizad
Total Records ( 4 ) for M. Dashtizad
  Hajarian Hadi , H. Wahid , O. Abas Mazni , Y. Rosnina , M. Daliri , M. Dashtizad , A. Faizah , K. C. Yap , F. J. Fahrul and A. Fazly
  Problem statement: Vitrification is replacing conventional slow freezing to cryopreserve gametes and embryos especially for in vitro production of embryo in domestic animal species. However, the results are still not satisfactory. The aim of this experiment was to study the effect of different equilibration temperatures on in vitro viability of immature bovine oocytes after vitrification. Approach: Oocytes were obtained from slaughterhouse ovaries. Only grade one oocytes were used. Oocytes were equilibrated in three different temperatures: 32, 37, or 41°C. Immature oocytes were equilibrated in VS1 (7.5 Ethylene Glycol (EG) + 7.5% DMSO) for 10-12 min and then exposed to VS2 (15% EG + 15%DMSO + 0.5M sucrose) for one min. Thereafter oocytes were loaded on hand-made Cryotop and directly plunged into liquid nitrogen. After warming, oocytes were examined for viability, maturation, cleavage and blastocyst production. Results: Oocytes that were equilibrated at 37°C had significantly higher (p<0.05) viability than 41°C, but there were no significant difference between 37 and 41 with 32°C. Maturation rate in 37°C group was significantly higher compared with other groups. The highest percentage of degenerated and germinal vesicle stage oocytes were obtained from 41°C than 32 and 37°C. Cleavage rate of 37°C group (38.77%) was greater than other groups (30.84 and 28.95% for 32 and 41°C, respectively). The highest blastocyst rate was also produced when oocytes equilibrated at 37°C (6.45%). Conclusion: In conclusion, these results indicated that immature bovine oocytes can be equilibrated successfully at 37°C while higher or lower temperature can significantly decrease their subsequent viability and development.
  Hajarian Hadi , H. Wahid , Y. Rosnina , M. Daliri , M. Dashtizad , H. Karamishabankareh , A. Faizah , M.I. Iswadi and O. Abas Mazni
  Beside cooling/warming rates and composition of vitrification solution, developmental stage of immature oocytes may also affect their vitrification outcome. The aim of the present study was to evaluate the selection effect of developmentally competent immature bovine oocytes by Brilliant Cresyl Blue (BCB) on maturity of oocytes after vitrification. Oocytes were obtained from slaughterhouse ovaries. Only oocytes with 4-5 layers of cumulus cells and homogenous cytoplasm were used. After exposure to BCB stain, immature oocytes were divided into colored (BCB+) and colorless (BCB-) cytoplasm groups. Immature oocytes were equilibrated in VS1 (7.5 Ethylene Glycol (EG)+7.5% DMSO) for 10-12 min and then exposed to VS2 (15% EG+ 15% DMSO+0.5M sucrose) for 1 min. Thereafter, oocytes were loaded on Cryotop and directly plunged into liquid nitrogen. After warming, oocytes were examined for presence of polar body and nuclear maturity. Higher number of oocytes in BCB+group extruded first polar body in comparison with other vitrified groups but not significantly (p>0.05). Compared to the BCB- oocytes, there was significantly lower percentage of degeneration for BCB+oocytes (p<0.05). Within vitrified groups, reaching to the MII stage was significantly higher in BCB+group (51.5%) compared with BCB and vitrified-control groups (27.9 and 40.3%, respectively). These results indicated that selection of potent immature bovine oocytes using brilliant cresyl blue improved the nuclear maturity of immature oocytes after vitrification. In addition, this selection can be a valuable tool to improve the vitrification outcome.
  H. Hajarian , H. Wahid , Y. Rosnina , M. Daliri , M. Dashtizad , T. Mirzapour , N. Yimer , M.M. Bukar , M.I. Iswadi and O. Abas Mazni
  The aim of this study was to evaluate the effectiveness of different cryodevices (Open Pulled Straw (OPS), Electron Microscopy Grid (EMG) and cryotop for vitrification of immature bovine oocytes. Polar body, MII stage, survivability and subsequent developmental rates were compared. Only oocytes with 4-5 layers of cumulus cells were used. Oocytes were equilibrated in the first vitrification solution (VS1; HS+10% DMSO+10% Ethylene Glycol (EG)) for 30-45 sec and then in the second vitrification solution (VS2; 20% DMSO+20% EG+0.5 M Sucrose) for 25 sec. Within 30 sec they were mounted on one of the cryodevices and directly plunged into Liquid Nitrogen (LN2) for 10 days. Immature oocytes vitrified using cryotop represented higher rate of polar body extrusion and nuclear maturity (p<0.05). The highest survivability resulted from cryotop and EMG groups and no significant difference found between them. Vitrified oocytes in cryotop group had highest cleavage and blastocyst rates. All of the mean measured rates for vitrified/warmed immature oocytes were significantly lower than that of control group (p<0.05). In conclusion, results of this study showed the superiority of cryotop device for vitrification of immature bovine oocytes which resulted in higher viability and subsequent embryo development.
  M. Dashtizad , H. Wahid , O. Abas Mazni , Y. Rosnina , M. Daliri and H. Hajarian
  Development of efficient culture system to support embryonic development would be valuable when percentage of produced embryos reaching to the blastocyst stage is important. However, the rate of bovine embryo production in vitro is still lower than expected. Present study was performed to investigate the effect of ghrelin on nuclear maturation and subsequent bovine embryo development in vitro. Cumulus-oocyte-complexes were collected from slaughterhouse ovaries and randomly allocated in each treatment groups. Five different concentrations of ghrelin (0, 5, 50, 500 and 1000 ng mL-1) were added to the in vitro maturation medium (Hepes-buffered medium 199+fetal calf serum+gonadotrophins+insulin+antibiotics). The proportion of oocytes developed to metaphase II stage was significantly increased at 5 and 50 ng mL-1 ghrelin (86.32±3.38 and 89.77±2.92%, respectively). The result also indicated that adding high concentration of ghrelin adversely affect (p<0.05) the nuclear maturation rates of bovine oocytes. However, the subsequent embryo development was not significantly affected by addition of ghrelin to the IVM medium. This study showed that inclusion of 5-50 ng mL-1 ghrelin in maturation medium may have beneficial effects on nuclear maturation of bovine oocytes in vitro.
 
 
 
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