Hainan Provincial Key Laboratory for Human Reproductive Medicine and Genetic Research, Hainan Provincial Clinical Research Center for Thalassemia, National Center for International Research, The First Affiliated Hospital of Hainan Medical University, Hainan Medical University, Haikou, Hainan, China; Haikou Key Laboratory for Preservation of Human Genetic Resource, The Key Laboratory of Tropical Translational Medicine of Ministry of Education, The First Affiliated Hospital of Hainan Medical University, Haikou, Hainan, China.
College of Medical Laboratory Science, Guilin Medical University, Guilin 541004, Guangxi, China.
Eur J Obstet Gynecol Reprod Biol. 2024 Nov;302:26-32. doi: 10.1016/j.ejogrb.2024.08.039. Epub 2024 Aug 29.
Multinucleated blastomeres at the two-cell stage (2MNB) represent a frequently observed nuclear abnormality in early human embryos. This abnormality has been reported to significantly impact on the embryo's developmental potential to reach the blastocyst stage. However, our understanding of the embryo's developmental potential and the morphokinetics of 2MNB remains limited. This study investigates the influence of 2MNB and its subtypes on the blastocyst formation.
A non-interventional retrospective study was performed in the Reproductive Medical Center of the First Affiliated Hospital of Hainan Medical University, using a time-lapse incubator. The study involved the evaluation of 4416 embryos, including 628 multinucleated embryos, from 1521 intracytoplasmic sperm injection (ICSI) cycles conducted between October 2019 and October 2021. The morphokinetic characteristics of multinucleated embryos were analyzed.
The results show multinucleation was the most common abnormal mitotic event during embryo development (14.22 %) in 4416 embryos. A control group of 3210 developmentally normal embryos was used in the study. The multinucleated blastomeres caused a lower blastocyst rate (52.48 % VS 64.02 %) compared to the control group. Whereas, 2MNBcause a higher blastocyst rate thanthemat the 4-cell stage (4MNB) (58.89 % VS 43.64 %). 2MNB can be further be further divided into 2MNB and 2MNB based on one multinucleated blastomere or two multinucleated blastomere appeared. Time to pronuclei fading (tPNf) is significantly longer in 2MNB compared to 2MNB. Furthermore, the 2MNB embryos were divided into four subgroups (Bi-: two nuclei with almost the same size, Micro-: two nuclei with varying sizes, Poly-: more than two nuclei with almost the same size, and Cluster-: more than two nuclei with varying sizes) based on the number of nuclei and relative size. The results show that the Bi- and Micro- groups had a significantly increased blastocyst rate. The Cluster-, and Poly- groups showed significantly delayed embryonic development compared to normal controls. Bi-group has significant delays at t3, t5, and t8 and the Micro-group had a significant delay only at t8.
2MNB cause higher blastocyst rate than them at 4MNB. 2MNB shows shorter tPNf compared to 2MNB. Moreover, the Micro-, Bi- groups had a significantly increased blastocyst rate and different kinetic parameters compared to Cluster-, Poly-groups, suggesting that it is necessary to distinguish the nucleus status within 2MNB to increase the blastocyst rate. When selecting embryos for transformation from the 2MNB, Micro- is the best choice.
在两细胞期（2MNB）的多核胚胎是人类早期胚胎中经常观察到的核异常。据报道，这种异常显著影响胚胎发育到达囊胚阶段的潜能。然而，我们对胚胎发育潜能和 2MNB 的形态动力学的理解仍然有限。本研究调查了 2MNB 及其亚型对囊胚形成的影响。
这是一项在海南医学院第一附属医院生殖医学中心进行的非介入性回顾性研究，使用时差培养箱。该研究评估了 2019 年 10 月至 2021 年 10 月期间进行的 1521 个胞浆内单精子注射（ICSI）周期中的 4416 个胚胎，包括 628 个多核胚胎。分析了多核胚胎的形态动力学特征。
结果显示，多核化是 4416 个胚胎中最常见的异常有丝分裂事件（14.22%）。研究中使用了 3210 个发育正常的胚胎作为对照组。与对照组相比，多核胚胎的囊胚率较低（52.48%对 64.02%）。而 2MNB 的囊胚率高于 4 细胞期（4MNB）（58.89%对 43.64%）。2MNB 可进一步分为一个或两个多核胚胎出现的 2MNB 和 2MNB。与 2MNB 相比，2MNB 的原核消失时间（tPNf）明显更长。此外，根据核的数量和相对大小，将 2MNB 胚胎分为四个亚组（Bi-：两个大小几乎相同的核，Micro-：两个大小不同的核，Poly-：两个以上大小几乎相同的核，Cluster-：两个以上大小不同的核）。结果表明，Bi-和 Micro-组的囊胚率显著增加。与正常对照组相比，Cluster-和 Poly-组的胚胎发育明显延迟。Bi 组在 t3、t5 和 t8 时出现明显延迟，Micro 组仅在 t8 时出现明显延迟。
2MNB 的囊胚率高于 4MNB。与 2MNB 相比，2MNB 的 tPNf 更短。此外，与 Cluster-、Poly-组相比，Micro-、Bi-组的囊胚率和不同的动力学参数显著增加，表明有必要区分 2MNB 内的核状态以提高囊胚率。当从 2MNB 中选择胚胎进行转化时，Micro-是最佳选择。
