3D+time imaging of normal and twin sea urchin embryos for the reconstruction of their cell lineage.

Abstract

The Mediterranean sea urchin, Paracentrotus lividus, has been a powerful model to study embryonic development since the late 1800s. As a model, it has the advantage of having external fertilization, it can easily be manipulated experimentally, and it has semi-transparent embryonic stages, which makes it ideal for live imaging. Embryogenesis is a highly dynamic process with intrinsic variability. The reconstruction of cell dynamics and an assessment of such variability from in vivo observations has proven to be a challenge. Here, we provide an innovative methodology for manipulation and immobilization of embryos and their long-term 3D+time imaging. We then describe the twinning procedure that allows us to assess the variability and robustness of developmental processes. We demonstrate the reconstruction of cell lineages based on automated image processing and cell tracking using the BioEmergences workflow as well as the use of interactive visualization tools (Mov-IT software) for lineage validation, correction and analysis.