Characterization of Oocytes For in vitro FertilizationUsing Electrical Impedance Spectroscopy

卵母细胞体外受精(IVF)是人类和动物辅助生殖的既定程序。当自然交配失败，或者家畜和研究哺乳动物必须保存和繁殖时，试管受精是例行公事。体外受精关键取决于卵母细胞的质量，特别是透明带(ZP)的状态，ZP由细胞外基质的凝胶外层组成，在卵母细胞分离和培养过程中会自发硬化，使精子无法穿透。通常通过光学检查来判断卵母细胞的质量。这种方法是观察者偏向的。在这里，我们建议使用阻抗频谱(EIS)来表征小鼠的卵母细胞，因为这项技术是独立于观察者的，并且是非破坏性的，因此可以对成熟的卵母细胞和发育中的胚胎进行纵向实时观察。该项目的目标是开发一种集易用性、小型化、集成化和便携性于一体的合适的测量装置。最终，我们将通过EIS表征单个小鼠卵母细胞ZP的时间分辨硬化。我们将利用已知ZP结构和加工缺陷的小鼠的遗传品系来研究卵母细胞阻抗谱变化的分子基础。使用宽频率范围的EIS测量，我们将研究ZP糖蛋白基质的变化引起的阻抗变化，与卵母细胞细胞质的电生理变化分开。我们将建立EIS作为一种非破坏性的方法，以独立于观察者的方式来判断卵母细胞的质量，以最终提高辅助生殖技术的受精率。

Oocyte in vitro fertilization (IVF) is an established procedure in human and animal assisted reproduction. IVF is routinely employed when natural mating fails, or when livestock and research mammals must be preserved and propagated. IVF critically depends on the quality of oocytes, especially on the state of the zona pellucida (ZP) which comprises a gelatinous outer layer of extracellular matrix that spontaneously hardens and becomes impenetrable to sperm during oocyte isolation and culture. Oocyte quality is typically judged by optical inspection. This method is observer-biased. Here, we propose to employ electrical impedance spectroscopy (EIS) for mice oocyte characterization, because this technique is observer independent, as well as non-destructive thus allowing longitudinal live observation of maturing oocytes and developing embryos. The objective of the project is to develop a suitable measurement setup combining ease of use, miniaturization, integration, and portability. Ultimately, we will characterize time-resolved the hardening of the ZP of single mice oocytes by EIS. We will study the molecular basis of changes in impedance spectra of oocytes by using genetic strains of mice with known deficiencies in ZP structure and processing. Using EIS measurements over a wide frequency range, we will study impedance changes caused by changes in the ZP glycoprotein matrix, separate from electrophysiological changes in the oocyte cytoplasm. We will establish EIS as a non-destructive method to judge oocyte quality in an observer-independent manner to ultimately increase the fertilization rate in assisted reproductive technology.