Serial block-face scanning electron microscopy of Schmidtea mediterranea.

The flatworm planarian, Schmidtea mediterranea (Smed) is a master at regenerating and rebuilding whole animals from fragments. A full understanding of Smed's regenerative capabilities requires a high-resolution characterization of organs, tissues, and the adult stem cells necessary for regeneration in their native environment. Here, we describe a serial block face scanning electron microscopy (SBF-SEM) protocol, optimized for Smed specifically, for visualizing the ultrastructure of membranes and condensed chromosomes in this model organism.