Whole embryo biomechanics with reverberant optical coherence elastography

Many morphogenesis processes during embryo development are fundamentally biomechanical processes, and disruption of these events can lead to debilitating congenital abnormalities. Imaging the biomechanical properties of embryos could provide insight into developmental disorders and could open new therapy avenues. However, current methods are invasive and are incapable of producing viscoelasticity maps of live samples in 3D. To overcome these limitations, we propose the use of reverberant shear wave fields in combination with optical coherence tomography (OCT) for high-resolution elastography at different developmental stages of murine embryos. A 1 kHz quasi-harmonic stimulation was applied to induce the diffuse shear field, which leveraged the heterogeneous microstructure and boundaries of the different tissue segments in the embryos. With this approach, we show how the shear wave speed (i.e., stiffness) of the spine, heart, and mid-brain increased as the embryo developed from embryonic day (E) 9.5 to E 11.5 at five separate stages. This noncontact technique is a promising method for imaging the biomechanical properties of different embryo structures during development with important applications for understanding developmental diseases and exploring treatments.