Abstract
Planarians are flatworms with almost unlimited regenerative abilities, which make them an excellent model for stem cell-based regeneration. To study the process of regeneration at the cellular level, immunohistochemical staining methods are an important tool, and the availability of such protocols is one of the prerequisites for mechanistic experiments in any animal model. Here, we detail protocols for paraffin embedding and immunostaining of paraffin sections of the model species Schmidtea mediterranea. This protocol yields robust results with a variety of commercially available antibodies. Further, the procedures provide a useful starting point for customizing staining procedures for new antibodies and/or different planarian species.