Vitrification is a superior method for cryopreservation of IVF embryos, but due to complicated warming protocols, it is not commonly used for commercial bovine embryos routine. To overcome the need of laboratory embryo preparation during warming, we developed an in-straw warming protocol compatible with most vitrification devices for embryo transfer without sucrose gradient steps and embryo evaluation. Surprisingly, one of the tested protocols improved embryo survival (95.0%* vs 83.1% expansion rate and 74.2%* vs 51.5% hatching rate) compared to conventional in-plate warming. Embryo quality was also increased, taken by the higher total cell numbers (160.7 ± 8.6* vs 99.0 ± 7.9) and lower apoptosis index (4.9 ± 0.6* vs 11.5 ± 2.4) 48 h after warming. Pregnancy rates were similar between vitrified-warmed embryos and fresh embryos (40% vs 43%). Based on our results, we suggest in-straw warming should always be used for vitrified embryos due to beneficial effects. Direct transfer can be safely performed using this protocol.

中文翻译：

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吸管内加热方案可提高玻璃化胚胎的存活率，并允许直接转移到牛体内

玻璃化冷冻是 IVF 胚胎冷冻保存的一种优越方法，但由于复杂的升温协议，它不常用于商业牛胚胎常规。为了克服加热过程中实验室胚胎制备的需要，我们开发了一种与大多数玻璃化冷冻设备兼容的吸管加热协议，用于胚胎移植，无需蔗糖梯度步骤和胚胎评估。令人惊讶的是，与传统的板内加热相比，其中一项测试方案提高了胚胎存活率（95.0%* 对 83.1% 的扩增率和 74.2%* 对 51.5% 的孵化率）。胚胎质量也有所提高，原因是升温 48 小时后细胞总数较高（160.7 ± 8.6* 对 99.0 ± 7.9）和细胞凋亡指数较低（4.9 ± 0.6* 对 11.5 ± 2.4）。玻璃化加热胚胎和新鲜胚胎的妊娠率相似（40% 对 43%）。根据我们的结果，由于有益效果，我们建议应始终对玻璃化胚胎使用吸管内加热。使用此协议可以安全地执行直接传输。