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

Abstract

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.

Effects of L-carnitine and cryodevices on the vitrification and developmental competence of invitro fertilized buffalo oocytes

“…Thus, supplementation of the basic vitrification medium with LC may avoid that damage (El-Shalofy et al, 2017). The oxidative activity of mitochondria is decreased mildly by vitrification, but increased by adding LC to vitrification medium in mice (Moawad et al, 2019). Furthemore, it is important to notice that according to our results, there is different threshold of LC for different cryo-devices.…”

“…The recovery rate was defined as the number of oocytes counted after the end of rehydration compared to the total number of oocytes vitrified (Moawad et al, 2019). Vitrified /warmed oocytes were examined under a stereomicroscope for evaluation of their morphological characteristics as reported by Sharma et al, (2010).…”

“…Trypan blue solutions (0.05%) were prepared by dissolving trypan blue in phosphate buffer saline (PBS; pH = 7.0). Oocyte staining was performed at room temperature for 2 min (Mostagir et al, 2019;Moawad et al, 2019).Oocytes (n= 806) were categorized based on the degree of dye exclusion. Unstained oocytes were classified as live and fully stained oocytes were considered dead (Moawad et al, 2019).…”

“…Cryopreservation is used to enhance the handling of gametes from buffalo for both research and commercial purposes (Attanasio et al, 2010). Moreover, cryopreservation of oocytes collected from slaughtered animals of high genetic value offers a chance to overcome the loss of valuable germplasm and to enhance genetic improvement of this species (Wani et al, 2004;Moawad et al, 2019).…”

“…L-carnitine also has antioxidant activity that protects cells from DNA damage (Jiang et al, 2012;Lahneche et al, 2019). The double role of LC as an antioxidant and an essential component of lipid metabolism makes it a promising agent for improving oocyte cryopreservation efficacy and subsequent embryonic development (El-Shalofy et al, 2017;Moawad et al, 2019).…”