Effects of cryoprotectants and cryoprotectant combinations on viability and maturation rates of Camelus dromedarius oocytes vitrified at germinal vesicle stage

Contents Camel fertility faces many problems, which could be solved by assisted reproductive technologies (ARTs). We designed the experiment to explore the effect of different cryoprotectant concentrations and combinations on viability and maturation rates of vitrified/warmed camel oocytes. We collected ovaries directly after slaughtering from local abattoir and transported them to laboratory in a thermo-flask containing normal physiological saline. We aspirated the oocytes from follicles, which is 2-8 mm in diameter, washed three times in TCM-199 and then examined under stereo-microscope for selection. We selected morphologically normal oocytes with an evenly granulated cytoplasm and a compact cumulus cell layer. We equilibrated morphologically normal oocytes in equilibration solution (ES), which is half concentration of vitrification one. After equilibration, We transported oocytes to vitrification solution using ethylene glycol (EG, 40%), dimethyl sulphoxide (DMSO, 40%) and EG 40% + DMSO 40%. The obtained results revealed that addition of EG 40% + DMSO 40% resulted in the best quality of vitrified/warmed oocytes, which is demonstrated by higher per cent survival rate (90.16%) and maturation rate (58.95%). While DMSO 40% resulted in 62.79% and 29.54%, respectively, EG 40% reported 86.11% and 53.47%, respectively. We could conclude that vitrification of immature camel oocytes by using 40% EG + 40% DMSO is suitable methods to limit drawbacks of vitrification methods, and we need further studies to assess the ability of in vitro-produced blastocyst to develop in vivo and establish pregnancy after embryo transfer.