[Cilia and neuronal migrations]

In a landmark paper published in 1977, G. Albrecht-Buehler described a primary cilium on the surface of migrating fibroblasts, and noticed that cilia are oriented parallel to the direction of migration of fibroblasts. While the presence of a primary cilium on neural progenitors and on post-mitotic neurons was noted long ago, it has been observed on migrating cortical interneurons only recently. As in fibroblasts, the cilium of interneurons controls the directionality of migration. It plays an important role in the reorientation of cortical interneurons towards the cortical plate. The morphogen Shh, which is expressed in the migratory pathway of interneurons, is one of the signals that control this reorientation.