AMPHIOXUS NEUROGLIA: MOLECULAR CHARACTERIZATION AND EVIDENCE FOR EARLY COMPARTMENTALIZATION OF THE DEVELOPING NERVE CORD

Glial cells play important roles in the development and homeostasis of metazoan nervous systems. However, while their involvement in the development and function in the central nervous system of vertebrates is increasingly well understood, much less is known about invertebrate glia and the evolutionary history of glial cells in metazoans. An investigation into amphioxus glia provides a window on the role of glial cells development and function at the transition between invertebrates and vertebrates, as this organism is the best living proxy for the last common ancestor of all chordates. We report our findings1 on amphioxus glia as characterized by molecular probes correlated with anatomical data at the TEM level. The results show amphioxus glial lineages express genes typical of vertebrate astroglia and radial glia and segregate early in development, forming what appears to be a spatially separated cell proliferation zone positioned laterally, between the dorsal and ventral zones of neural cell proliferation. Our study provides strong evidence for the presence of vertebrate-type glial cells in amphioxus.