Among echinoderms, crinoids are well known for their remarkable regenerative potential. Regeneration depends mainly on progenitor cells (undifferentiated or differentiated), which migrate and proliferate in the lesion site. The crucial role of the "progenitor" elements involved in the regenerative processes, in terms of cell recruitment, sources, and fate, is a central problem in view of its topical interest and biological implications. The spectacular regenerative potential of crinoids is used to replace lost internal and external organs. In particular, the process of arm regeneration in the feather star Antedon mediterranea is the regeneration model most extensively explored to date. We have addressed the morphological and functional characterization of the cell phenotypes responsible for the arm regenerative processes by using an in vitro approach. This represents the first successful attempt to culture cells involved in crinoid regeneration. A comparison of these results with others from previous in vivo investigations confirms the diverse cell types contributing to regeneration and underscores their involvement in migration, proliferation, and dedifferentiation processes.