Live-cell fluorescence imaging of echinoderm embryos

The rapid development, simplicity and optical clarity of the sea urchin embryo make it an excellent model system for studying the dynamic events of early development. An ever-growing palette of fluorescent proteins and biosensors can now be applied to studying sea urchin development, and there are now a wide variety of imaging modes that can be employed to image sea urchin embryogenesis. However, when performing live-cell imaging, one must take into consideration the sensitivity of embryos (and fluorescent probes) to the intense light associated with confocal microscopes. Here, we discuss general considerations for keeping embryos viable on the microscope stage, as well as probes for imaging cellular membranes and the cytoskeleton. We compare the relative merits of different confocal microscopes for live imaging of embryos and describe the potential for live-cell super-resolution microscopy.