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Fig. 4
Putative lamprey NECs are not neural crest-derived.
(a) Schematic larval lamprey section (modified from Barreiro-Iglesias et al., 2009) showing gill pairs in the orobranchial cavity, supported by an interbranchial septum, and a single gill at higher power. (b) Schematic Piavis-stage 17 (E19) lamprey (modified from Tahara,1988). Dotted line shows section plane in c,d,i,j,n. (c) Hematoxylin and eosin staining at E19 shows internal gills as ‘stalks’ within the orobranchial cavity. (d) Putative NECs (serotonergic cells associated with HNK1 epitope-immunoreactive neurites) are first visible at E18.5 in the medial gill epithelium. (e) Schematic (modified from Tahara,1988) showing neural crest labelling by DiI injection at E5 (Piavis stages 11–12). (f–n) Two different embryos (f–j, k–n), showing DiI-labeled neural crest cells migrating ventrally (arrowheads, g,l) into the branchial arches, contributing to branchial arch basket and gill supporting cells (arrowheads, j,n), but not serotonergic cells (putative NECs) in the orobranchial epithelium (i,j) or gills (n). 5-HT, serotonin; Ba, branchial arch; Bab, branchial arch basket; En, endostyle; Gs, gill seam; Is, interbranchial septum; Nc, notochord; Nt, neural tube; Obc, orobranchial cavity. Scale-bar: 50 μm.