Poro-viscoelastic behaviour of the zona pellucida: Impact of three-dimensional modelling on material characterisation

The development of objective biomarkers for the qualitative assessment of oocytes prior to in-vitro fertilisation procedures is crucial, and in this respect the mechanical response of cells has already emerged as a promising and valid measure. The test setups derived from this conceptual approach us...
Ausführliche Beschreibung

The development of objective biomarkers for the qualitative assessment of oocytes prior to in-vitro fertilisation procedures is crucial, and in this respect the mechanical response of cells has already emerged as a promising and valid measure. The test setups derived from this conceptual approach usually induce complex, partly asymmetric deformation states, so that the process of material parameter identification can only be realised via three-dimensional, mathematical models. In the present study, a three-dimensional model for oocytes is proposed and implemented in the form of the finite element method. In particular, the contribution of each cellular component to the overall mechanical response is considered by including an anisotropic poro-, viscoelastic approach for the zona pellucida and an incompressible neo-Hookean material for the ooplasm. The model is calibrated and validated using experiments on porcine oocytes under plate-plate compression and indentation during quasi-static cyclic and relaxation tests. In addition to investigating the influence of glycoprotein orientation on the shape and extent of deformation, the applicability of the model to identify mechanical properties is demonstrated and discussed in relation to real, complex testing devices. Ausführliche Beschreibung