[Boundary cap cells--a nest of neural stem cells in the peripheral nervous system].
The peripheral nervous system (PNS) is formed by neural crest cells (NCC) that migrate out of the neural tube in early mid-gestation. NCC give rise to most components of the PNS, including sensory neurons, glial satellite cells and Schwann cells. Neural crest cells also give rise to another type of PNS cell population named boundary cap (BC) cells, that form clusters at the surface of the neural tube, at entry and exit points of peripheral nerve roots. Using various genetic tools we were able to trace BC cell progeny during development and to ablate them in vivo. This revealed a previously unsuspected function of BC cells: they are required to maintain the integrity of the spinal cord motor column as, in their absence, motor neurons translocate their cell bodies along their axons into the periphery. In addition, we found that trunk BC-derived cells migrated along peripheral axons and colonized spinal nerve roots and dorsal root ganglia (DRG). All Schwann cell precursors occupying the dorsal roots were derived from BC cells. In the DRG, BC-derived cells were the progenitors of both neurons (mainly nociceptive afferents) and satellite cells. These unexpected observations indicate that BC cells constitute a source of peripheral nervous system (PNS) components that, after the major neural crest ventrolateral migratory stream, feed a secondary wave of migration to the PNS.
Topilko
Piotr
P
Laboratoire de Génétique Moléculaire du Développement, Inserm 784, Ecole Normale Supérieure, 45, rue d'Ulm, 75230 Paris cedex 05, France. topilko@biologie.ens.fr
D000818:Animals; D001369:Axons / Q000648:ultrastructure; D019070:Cell Lineage; D002465:Cell Movement; D002642:Chick Embryo; D004167:Diphtheria Toxin / Q000235:genetics; D051767:Early Growth Response Protein 2 / Q000235:genetics / Q000502:physiology; D005727:Ganglia, Spinal / Q000166:cytology; D006801:Humans; D051379:Mice; D009046:Motor Neurons / Q000166:cytology; D016254:Mutagenesis, Insertional; D009432:Neural Crest / Q000166:cytology*; D017933:Peripheral Nervous System / Q000166:cytology*; D012583:Schwann Cells / Q000166:cytology; D013116:Spinal Cord / Q000166:cytology / Q000196:embryology; D013126:Spinal Nerve Roots / Q000166:cytology; D013234:Stem Cells / Q000166:cytology*
D004167:Diphtheria Toxin; D051767:Early Growth Response Protein 2; C497327:Egr2 protein, mouse