This study aimed to evaluate the effect of different cryodevices [conventional straws (CS) and open pulled straws (OPS)] of vitrification on viability, morphology and ultrastructure of ovine immature oocytes. Ovaries of slaughtered ewes were transported from a local abattoir to our laboratory in 0.9 % normal saline at 25–30 °C. The visible follicles (1–6 mm in diameter) were sliced with a microblade and their cumulus-oocyte complexes (COCs) were released in Dulbecco’s phosphate buffer saline. Upon examination under a stereomicroscope, good quality oocytes (n = 266) were selected and randomly assigned into three groups: 1) Fresh oocytes (control, n = 78); 2) Oocytes vitrified using CS (n = 95) and 3) Oocytes vitrified using OPS (n = 93). The gross morphology of COCs was evaluated under a stereomicroscope whilst their viability was evaluated in Trypan blue stained smear. Moreover, glutaraldehyde-fixed COCs (n = 45) were processed for transmission electron microscopy. It was observed that the proportion of recovered normal ovine oocytes after vitrification in OPS (89.24 %) was significantly higher (P < 0.05) than those vitrified in CS (73.68 %). Meanwhile, the proportion of abnormal oocytes was greater (16.84 %) in CS than OPS (8.60 %). The proportion of viable ooplasm and viable cumulus oocytes was significantly (P < 0.05) higher in the fresh group (88.88 %) than OPS (69.11 %) and CS (54.54 %) groups with significant (P < 0.05) difference between the two vitrification groups. Notably, ultrastructural alterations of vesicles and lipid droplets in fresh oocytes were similar with OPS and lower than CS vitrified-warmed oocytes without significant difference between the two vitrified groups. In conclusion, OPS vitrified-warmed oocytes have less cryoinjuries and higher survivability in comparison with CS vitrified-warmed oocytes, although ovine immature oocytes were more vulnerable to cryopreservation by vitrification.

这项研究旨在评估玻璃化的不同冷冻设备[常规吸管（CS）和敞开式吸管（OPS）]对绵羊未成熟卵母细胞的活力，形态和超微结构的影响。在25–30°C下，在0.9％的生理盐水中将屠宰的卵巢的卵巢从当地屠宰场运到我们的实验室。将可见的卵泡（直径为1-6 mm）切成微刀片，并将它们的积云切成薄片。卵母细胞复合物（COC）在Dulbecco的磷酸盐缓冲液中释放。在体视显微镜下检查后，选择高质量的卵母细胞（n = 266）并将其随机分为三组：1）新鲜卵母细胞（对照组，n = 78）；2）用CS玻璃化的卵母细胞（n = 95）和3）用OPS玻璃化的卵母细胞（n = 93）。在立体显微镜下评估COC的总体形态，而在锥虫蓝染色涂片中评估其生存力。此外，对戊二醛固定的COC（n = 45）进行了处理，以进行透射电子显微镜检查。观察到，在OPS中玻璃化后恢复的正常绵羊卵母细胞的比例（89.24％）显着高于在CS中玻璃化后的正常绵羊卵母细胞的比例（73.68％）。同时，CS中异常卵母细胞的比例（16.84％）大于OPS（8.60％）。新鲜组的卵丘卵母细胞显着（P <0.05）（88.88％）高于OPS（69.11％）和CS（54.54％）组，两个玻璃化组之间差异显着（P <0.05）。值得注意的是，新鲜卵母细胞中囊泡和脂质滴的超微结构变化与OPS相似，并且比CS玻璃化温卵母细胞低，两组之间没有显着差异。综上所述，OPS玻璃化温卵母细胞与CS玻璃化温卵母细胞相比，冷冻损伤少，存活率更高，尽管绵羊未成熟卵母细胞更容易通过玻璃化冷冻保存。