A chick–chick intraspecies chimera was created by removing the neural tube adjacent to somites 2–6 from a normal chick embryo at E1.5 and replacing it with equivalent tissue from an age-matched chick-GFP transgenic embryo. At E10, the colorectum was removed, sectioned, and stained with HNK-1 antibody (red) to detect neural crest-derived cells, and with DAPI (blue) to label nuclei. Vagal neural crest-derived cells are HNK-1+/GFP+, while sacral neural crest derived-cells, which comprise the nerve of Remak, are HNK-1+/GFP−. From Nagy et al., Developmental Dynamics 241:842–851, 2012. © 2012 Wiley Periodicals, Inc.