high levels of pan-neuronal genes (MAP2, NCAM1) yet are molecularly distinct (Figure 1C). Two clusters have high expression of PRPH, an intermediate neurofilament that is highly expressed in neurons of the peripheral nervous system and some central nervous system regions that have neural projections toward peripheral structures (Yuan et al., 2012). These two PRPH+ clusters segregate into a PHOX2B+ cluster and a POU4F1+ cluster (Figure 1D). The other neuronal cluster is marked by GPM6A expression, which is expressed throughout both the central nervous system (CNS) and the spinal cord during mouse development (Figure 1D) (Diez-Roux et al., 2011).
