Early cellular patterning is a critical step of embryonic development that determines the proper progression of morphogenesis in all metazoans. It relies on a series of rapid reductive divisions occurring simultaneously with the specification of the fate of different subsets of cells. Multiple species developmental strategies emerged in the form of a unique cleavage pattern with stereotyped division geometries. Cleavage geometries have long been associated to the emergence of canonical developmental features such as cell cycle asynchrony, zygotic genome activation and fate specification. Yet, the direct causal role of division positioning on blastomere cell behavior remain partially understood. Oriented and/or asymmetric divisions define blastomere cell sizes, contacts and positions, with potential immediate impact on cellular decisions, lineage specification and morphogenesis. Division positions also instruct daughter cells polarity, mechanics and geometries, thereby influencing subsequent division events, in an emergent interplay that may pattern early embryos independently of firm deterministic genetic programs. We here review the recent literature which helped to delineate mechanisms and functions of division positioning in early embryos.

早期细胞模式是胚胎发育的关键步骤，它决定了所有后生动物形态发生的正确进展。它依赖于一系列与不同细胞亚群的命运同时发生的快速还原分裂。多种物种的发展策略以具有刻板划分几何形状的独特解理模式的形式出现。长期以来，卵裂几何形状与典型发育特征的出现有关，例如细胞周期不同步、合子基因组激活和命运规范。然而，分裂定位对卵裂球细胞行为的直接因果作用仍然部分理解。定向和/或不对称分裂定义了卵裂球细胞的大小、接触和位置，对细胞决策有潜在的直接影响，谱系规范和形态发生。分裂位置还指导子细胞的极性、力学和几何形状，从而影响随后的分裂事件，在一种新兴的相互作用中，可能独立于确定性遗传程序对早期胚胎进行模式化。我们在此回顾最近的文献，这些文献有助于描述早期胚胎中分裂定位的机制和功能。