Cells comprise mechanically active matter that governs their functionality, but intracellular mechanics are difficult to study directly and are poorly understood. However, injected nanodevices open up opportunities to analyse intracellular mechanobiology. Here, we identify a programme of forces and changes to the cytoplasmic mechanical properties required for mouse embryo development from fertilization to the first cell division. Injected, fully internalized nanodevices responded to sperm decondensation and recondensation, and subsequent device behaviour suggested a model for pronuclear convergence based on a gradient of effective cytoplasmic stiffness. The nanodevices reported reduced cytoplasmic mechanical activity during chromosome alignment and indicated that cytoplasmic stiffening occurred during embryo elongation, followed by rapid cytoplasmic softening during cytokinesis (cell division). Forces greater than those inside muscle cells were detected within embryos. These results suggest that intracellular forces are part of a concerted programme that is necessary for development at the origin of a new embryonic life.

细胞包含控制其功能的机械活性物质，但细胞内力学难以直接研究且了解甚少。但是，注入的纳米器件为分析细胞内的机械生物学提供了机会。在这里，我们确定了从受精到第一个细胞分裂的小鼠胚胎发育所需的力和细胞质机械特性变化的程序。注射的，完全内在化的纳米器件对精子的去浓缩和再浓缩有反应，随后的器件行为提出了基于有效胞质刚度梯度的核融合模型。纳米装置报告了染色体对齐过程中细胞质机械活性的降低，并表明细胞质变硬发生在胚胎伸长过程中，然后在胞质分裂（细胞分裂）过程中快速胞质软化。在胚胎中检测到的力量大于肌肉细胞内部的力量。这些结果表明细胞内力是一个协调的程序的一部分，该程序对于新的胚胎生命的起源是必需的。