Serial longitudinal sections at E8 (HH32) show ENCCs along the entire colorectum forming two plexuses of cells immunoreactive to ENCC markers N-cadherin (A), Sox10 (B), and L1CAM (C). Early neuronal differentiation is marked by Tuj1 (D) and Hu (E). Differentiation is more advanced in the submucosal than myenteric plexus, as shown by proximal (G) and distal (H) cross-sections (marked in (E)). NCAM is a later marker of neuronal differentiation (F), expressed by enteric neurons in the proximal (I), but not distal (J), colorectum at this stage. CN, another neuronal marker, is expressed throughout the colorectum (K), as is B-fabp, which marks glial cells and their precursors (L). B-fabp is only expressed by glial cells, not neurons, at E8 (HH32; M). By E9 (HH35), Sox-10 is expressed only by glial cells, as shown in the NoR (N), and not by enteric neurons (O), while L1CAM is downregulated in glial cells (P) and expressed only by the neurons (Q).