Successful cryopreservation of the important silkworm bioresource, Bombyx mori, is essential. In this study, we aimed for successful cryopreservation using vitrification of silkworm embryos. Furthermore, the embryos were assessed for the most appropriate sampling stage. We found that vitrified embryos developed to the serosa ingestion stage when they were vitrified at embryonic stage 24-25. The most suitable stage for vitrification was around a 5-10 h period when the tracheal fibers were elongating in stage 25. None of the vitrified embryos developed into larvae, although some did develop to the pre-hatching stage. From histological analysis, we found that several small cracks formed on the cuticle covering the hypodermis in the vitrified embryos. Additionally, the midgut epithelium was detached from the midgut wall and mixed with the yolk in the midgut lumen. We speculate that the vitrified embryos died from a rapid loss of body water from the small cracks formed in the cuticle. We also suggest that the vitrified embryos may have resulted in dysfunction of the midgut.

中文翻译：

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家蚕冻存的胚胎阶段选择及冻存对胚胎组织的影响

成功冷冻保存重要的家蚕生物资源家蚕至关重要。在这项研究中，我们的目标是使用家蚕胚胎的玻璃化冷冻成功进行冷冻保存。此外，胚胎被评估为最合适的取样阶段。我们发现玻璃化胚胎在胚胎阶段 24-25 被玻璃化时发育到浆膜摄取阶段。最适合玻璃化的阶段是大约 5-10 小时，此时气管纤维在第 25 阶段伸长。没有一个玻璃化胚胎发育成幼虫，尽管有些胚胎发育到了预孵化阶段。从组织学分析中，我们发现在玻璃化胚胎中覆盖皮下组织的角质层上形成了几条小裂缝。此外，中肠上皮与中肠壁分离并与中肠腔中的蛋黄混合。我们推测玻璃化胚胎的死亡是由于角质层中形成的小裂缝导致体内水分快速流失。我们还建议玻璃化胚胎可能导致中肠功能障碍。