FROM STEM CELLS TO MOTONEURONS
How mammalian stem cells produce specific neuronal subtypes remains elusive. A recent study shed light on the process by which motoneurons are generated from human embryonic stem cells (Xue-Jun Li e coll., Specification of motoneurons from human embryonic stem cells. Nature Biotechnology 23, 215-221, 2005).
Xue-Jun Li and his colleagues found that retinoic acid action is required during neuroectoderm induction for motoneuron specification and suggest that stem cells have restricted capacity to generate region-specific projection neurons even at an early developmental stage.