Organization of the nervous system in the model planarian Schmidtea mediterranea: an immunocytochemical study.

Freshwater planarians are an emerging model in which to study regeneration at the molecular level. These animals can regenerate a complete central nervous system (CNS) in only a few days. In recent years, hundreds of genes expressed in the nervous system have been identified in two popular planarian species used by several laboratories: Dugesia japonica and Schmidtea mediterranea. Functional analyses of some of those neural genes have allowed the process of CNS regeneration to begin to be elucidated in those animals. However, additional work is required to characterize the different neuronal populations. Thus, the identification or generation of antibodies that act as markers for specific neuronal cell types would be extremely useful not only in obtaining a more detailed characterization of the planarian nervous system but also for the analysis of phenotypes obtained by RNA interference. Here, I have used five different antibodies to describe different neuronal populations in the freshwater planarian S. mediterranea. This study represents a first step in characterizing the organization of the nervous system of this species at the cellular level.