IVIRMA Global Research Alliance, IVIRMA ITALIA, Rome, Italy.
IVIRMA Global Research Alliance, 9.baby, Bologna, Italy.
Hum Reprod. 2024 Nov 1;39(11):2392-2399. doi: 10.1093/humrep/deae186.
Cell cycle regulation is crucial to assure expansion of a cell population, while preserving genome integrity. This notion is especially relevant to fertilization and early embryo development, a time when the cell cycle transforms from meiotic into mitotic cycles. Zygote-to-embryo transition is acutely error-prone, causing major developmental perturbations, including cleavage delays, tri- and multi-chotomous cleavages, and cell fragmentation. Another such alteration is bi- and multinucleation, consisting of the simultaneous formation of two or more nuclei at interphase. Indeed, multinucleation affects a large proportion of early human embryos, typically at the two-cell stage. Mechanistically, several factors, including spindle dysfunction, failed cleavage, and cell fusion, may generate this cell anomaly. In assisted reproduction treatment, multinucleation is associated with reduced developmental rates and lower implantation rates in Days 2-3 embryo transfers. However, many multinucleated embryos can develop to the blastocyst stage. In blastocyst transfers, the current evidence does not suggest a major impact of a previous history of multinucleation on the odds of euploidy or successful treatment outcomes. Human embryo multinucleation remains a not-fully-understood but developmentally relevant and intriguing phenomenon which requires further research of its generative mechanisms and clinical implications.
细胞周期调控对于确保细胞群体的扩增和基因组完整性至关重要。这一概念在受精和早期胚胎发育中尤为重要，因为此时细胞周期从减数分裂转变为有丝分裂。从受精卵到胚胎的过渡非常容易出错，导致主要的发育紊乱，包括卵裂延迟、三裂和多裂以及细胞碎片化。另一种这样的改变是双核和多核化，包括在有丝分裂间期同时形成两个或更多核。事实上，多核化影响了很大一部分早期人类胚胎，通常在两细胞阶段。从机制上讲，纺锤体功能障碍、分裂失败和细胞融合等多种因素都可能导致这种细胞异常。在辅助生殖治疗中，多核化与胚胎发育率降低和第 2-3 天胚胎移植的着床率降低有关。然而，许多多核胚胎可以发育到囊胚阶段。在囊胚移植中，目前的证据表明，以前的多核化历史对整倍体的可能性或成功治疗结果没有重大影响。人类胚胎多核化仍然是一个尚未完全理解但与发育相关且引人入胜的现象，需要进一步研究其产生机制和临床意义。
