RESEARCH QUESTION The morula stage is a poorly understood developmental stage. In the morula, cell compaction can involve all or only some blastomeres, with largely unknown implications. Here, the prevalence, underlying morphokinetic mechanisms and possible consequences of partial compaction, were investigated. DESIGN Preimplantation genetic testing for aneuploidies (PGT-A) cycles of women whose embryos were observed by time-lapse technology were studied. PGT-A data, generated by array comparative genomic hybridization analysis and assessed in three age groups (≤34, 35-39 and ≥40 years), were obtained from trophectoderm biopsies after development to blastocyst stage. RESULTS Compaction occurred according to three modalities: (i) full compaction, with all blastomeres included (FCM); partial compaction (partially compacted morula [PCM]), with blastomeres (ii) excluded from the outset (excluded-PCM) or (iii) extruded after compaction (extruded-PCM). Partial compaction occurred more frequently than full compaction. Excluded-PCM displayed the slowest morphokinetics at most stages and were most often associated with abnormal cleavage. After compaction, embryo degeneration was more frequently associated with cell extrusion. In excluded-PCM, loss of ≥2 cells impacted blastocyst rate. In embryos of both younger and middle age groups, no statistical differences were observed in the rate of aneuploidy in relation to the three compaction groups, unlike what observed in ≥40 years women. Implantation rates after transfer of euploid blastocysts were not statistically different between the three groups. CONCLUSIONS Alternative modalities of incomplete compaction were detected. Such patterns are characterized by different morphokinetic behaviours overarching the entire preimplantation development, and by different developmental abilities.

中文翻译：

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胚胎部分压实的替代模式：患病率，吗啡运动史和可能的影响。

研究问题桑ula虫阶段是一个鲜为人知的发育阶段。在桑ula中，细胞致密化可能涉及全部或仅一些卵裂球，其影响尚不为人所知。在这里，调查了患病率，潜在的形态动力学机制以及部分压实的可能后果。设计研究了通过延时技术观察胚胎的女性的非整倍性（PGT-A）周期的植入前遗传学测试。PGT-A数据是通过阵列比较基因组杂交分析生成的，并在三个年龄组（≤34岁，35-39岁和≥40岁）中进行了评估，这些数据是从滋养层到囊胚期的活检获得的。结果压实根据三种方式进行：（i）完全压实，包括所有卵裂球（FCM）；部分压实（部分压实桑ula [PCM]），卵裂球（ii）从一开始就排除在外（不包括PCM）或（iii）压实后被挤出（挤出PCM）。与完全压实相比，部分压实发生的频率更高。排除的PCM在大多数阶段显示出最慢的形态动力学，并且最常与异常分裂有关。压实后，胚胎变性更经常与细胞挤压相关。在排除的PCM中，≥2个细胞的丢失影响了胚泡率。在年轻和中年年龄组的胚胎中，与三个压实组有关的非整倍性比率均未观察到统计学差异，这与≥40岁的女性不同。三倍体囊胚转移后的植入率在三组之间无统计学差异。结论检测到不完全压实的替代方式。