Clonal Mapping of Astrocytes in the Olfactory Bulb and Rostral Migratory Stream.

Astrocytes are the most abundant glial population in the central nervous system, where they fulfill multiple essential tasks. Such diverse functions require a heterogeneous population of cells, yet it is still unclear how this cellular heterogeneity emerges during development. To clarify to what extent such diversity is determined by lineage, we have elaborated the first clonal map of astrocytes in the olfactory bulb and rostral migratory stream. Astrocyte clones are comprised of a limited number of cells, which arise from local progenitors and that are arranged following a radial pattern. Although astroglia exhibit a vast morphological diversity, this was layer-dependent rather than determined by lineage. Likewise, lineage did not strictly determine their position, although we found a striking relationship between the clones and olfactory glomeruli. A distinctive morphology and other clonal features, together with the occurrence of immature forms, reflect the singularity of these astroglial populations.