Research and Development Group, Zen-noh Embryo Transfer Center, Kamishihoro, Hokkaido, Japan; Department of Veterinary Medical Science, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
Research and Development Group, Zen-noh Embryo Transfer Center, Kamishihoro, Hokkaido, Japan.
Theriogenology. 2019 Jul 15;133:119-124. doi: 10.1016/j.theriogenology.2019.04.031. Epub 2019 Apr 27.
Time-lapse monitoring (TLM) has emerged as a novel technology for the continuous and noninvasive evaluation of embryos. TLM has revealed the prevalence of specific dysmorphisms such as abnormal development during the early-cleavage stage of embryos. However, little information is available on the prevalence and consequences of abnormal cleavage in bovine embryos. Hence, this study aimed to investigate growth potential of bovine embryos presenting abnormal cleavage, such as reverse cleavage (RC), direct cleavage (DC), and irregular and unsmooth ruffling of the oolema membrane (ruffling). Bovine embryos derived through in vitro fertilization (IVF) were cultured in the microwell culture dishes, and the kinetics of in vitro development were observed through TLM at 20-min intervals for 10 d. Approximately 36% of embryos that developed into a blastocyst presented abnormal cleavage. Morphokinetic evaluations revealed that RC, DC, and ruffling embryos showed slower development compared to embryos with normal cleavage (P < 0.01). Embryos with RC and DC, but not ruffling, revealed impaired hatchability (P < 0.05) with increased collapses of the blastocyst cavity until hatching (P < 0.0001). Moreover, the RC and DC embryos presented increased chromosomal aneuploidy (P < 0.05). These results suggest a compromised viability of embryos with RC and DC. This is the first report that clarified the effect of abnormal cleavage on the morphokinetics and growth potential of bovine IVF embryos. Results indicate that the kinetic evaluation of bovine embryos using the time-lapse imaging system will be beneficial for selecting embryos with a high viability.
延时监测 (TLM) 已成为一种用于连续、非侵入性评估胚胎的新技术。TLM 揭示了胚胎早期分裂阶段出现的特定畸形的普遍性，如发育异常。然而，关于牛胚胎异常分裂的流行率和后果的信息很少。因此，本研究旨在调查具有异常分裂的牛胚胎的生长潜力，如反向分裂 (RC)、直接分裂 (DC) 以及卵母细胞膜不规则和不光滑的起皱 (起皱)。通过体外受精 (IVF) 获得的牛胚胎在微孔培养皿中培养，并通过 TLM 以 20 分钟的间隔连续观察 10 天的体外发育动力学。大约 36%发育成囊胚的胚胎出现异常分裂。形态动力学评估显示，RC、DC 和起皱胚胎的发育速度比正常分裂胚胎慢 (P < 0.01)。RC 和 DC 胚胎而非起皱胚胎的孵化率降低 (P < 0.05)，囊胚腔的塌陷增加，直至孵化 (P < 0.0001)。此外，RC 和 DC 胚胎表现出染色体非整倍体增加 (P < 0.05)。这些结果表明 RC 和 DC 胚胎的生存能力受损。这是首次阐明异常分裂对牛 IVF 胚胎形态动力学和生长潜力的影响的报告。结果表明，使用延时成像系统对牛胚胎进行动力学评估将有助于选择具有高生存能力的胚胎。
