Processing Schmidtea mediterranea for Transmission Electron Microscopy: Classical and Microwave Techniques.

The flatworm Schmidtea mediterranea and related species are emerging model systems in such fields as stem-cell biology, regeneration, and evolutionary biology. Excellent molecular tools have been developed for S. mediterranea, but ultrastructural techniques have received less attention, which is unfortunate, as these methods are necessary to better understand the actual histological, cellular and subcellular features of regeneration and development. Tissue-processing regimens can be quite idiosyncratic for particular species or specimen types-what works for mammalian tissues or cell cultures will not necessarily give good results with freshwater planarians. Here we present detailed, optimized protocols for preparation of S. mediterranea by "standard" chemical fixation, and by a rapid microwave-based technique.