Du Yue, Chen Yizhe, Zhang Shuai, Cheng Dai, Liu Yaowei, Zhao Qili, Sun Mingzhu, Cui Maosheng, Zhao Xin
The Tianjin Key Laboratory of Intelligent Robotics, Institute of Robotics and Automatic Information System, Nankai University, Tianjin 300350, China.
Institute of Intelligence Technology and Robotic Systems, Shenzhen Research Institute of Nankai University, Shenzhen 518083, China.
Micromachines (Basel). 2022 Jul 8;13(7):1087. doi: 10.3390/mi13071087.
The early steps of embryogenesis are controlled exclusively by the quality of oocyte that linked closely to its mechanical properties. The mechanical properties of an oocyte were commonly characterized by assuming it was homogeneous such that the result deviated significantly from the true fact that it was composed of subcellular components. In this work, we accessed and characterized the subcellular components of the oocytes and developed a layered high-fidelity finite element model for describing the viscoelastic responses of an oocyte under loading. The zona pellucida (ZP) and cytoplasm were isolated from an oocyte using an in-house robotic micromanipulation platform and placed on AFM to separately characterizing their mechanical profiling by analyzing the creep behavior with the force clamping technique. The spring and damping parameters of a Kelvin-Voigt model were derived by fitting the creeping curve to the model, which were used to define the shear relaxation modulus and relaxation time of ZP or cytoplasm in the ZP and cytoplasm model. In the micropipette aspiration experiment, the model was accurate sufficiently to deliver the time-varying aspiration depth of the oocytes under the step negative pressure of a micropipette. In the micropipette microinjection experiment, the model accurately described the intracellular strain introduced by the penetration. The developed oocyte FEM model has implications for further investigating the viscoelastic responses of the oocytes under different loading settings.
胚胎发生的早期步骤完全由与卵母细胞机械特性紧密相关的卵母细胞质量控制。卵母细胞的机械特性通常通过假设其为均匀的来表征，这样的结果与它由亚细胞成分组成的真实情况有显著偏差。在这项工作中，我们获取并表征了卵母细胞的亚细胞成分，并开发了一个分层的高保真有限元模型来描述卵母细胞在加载下的粘弹性响应。使用内部机器人微操作平台从卵母细胞中分离出透明带（ZP）和细胞质，并将其放置在原子力显微镜（AFM）上，通过用力钳技术分析蠕变行为来分别表征它们的机械轮廓。通过将蠕变曲线拟合到开尔文 - 沃伊特模型来推导该模型的弹簧和阻尼参数，这些参数用于定义ZP和细胞质模型中ZP或细胞质的剪切松弛模量和松弛时间。在微吸管抽吸实验中，该模型足够准确地给出了在微吸管阶跃负压下卵母细胞随时间变化的抽吸深度。在微吸管显微注射实验中，该模型准确地描述了由穿透引入的细胞内应变。所开发的卵母细胞有限元模型对于进一步研究卵母细胞在不同加载设置下的粘弹性响应具有重要意义。
