“…Although all these motor neurons originate from a common precursor population in ventral neural tube and share many features in common at maturity, each motor pool has unique distinguishing characteristics. Neurons within an individual motor pool reside in a characteristic position in the LMC (Landmesser, 1978), exhibit a distinctive pattern of spontaneous electrical activity (Milner and Landmesser, 1999), express a unique set of LIM homeodomain and ETS transcription factors and cadherins (Tsuchida et al, 1994;Lin et al, 1998;Price et al, 2002), innervate a single target muscle, and receive monosynaptic input from sensory neurons supplying the same muscle (reviewed in Chen et al, 2003). These distinguishing properties of motor pools arise through the sequential activation of different transcriptional networks (reviewed in Shirasaki and Pfaff, 2002).…”