Fig. 4

Go-opsin+ cells and potentially co-expressed genes in developmental stages of the scaphopod Antalis entalis. Anterior faces up in all aspects. Early trochophores (a–c) express go-opsin in the region around the mouth (asterisk), while eya+ cells are distributed throughout the interior of the larva. Six1/2+ cells are located in the region of the foot (black arrow), in the prospective cerebral ganglia (cg), and in two other cells (white-lined arrow). In early mid-stage trochophores (d–i) go-opsin+ cells are located in the inner anterolateral mantle margin (arrows). Two other go-opsin+ cells are located in the lateral episphere adjacent to the trochoblasts (arrowheads). f Axons of the apically located go-opsin+ cells run to the neuropil of the apical organ (double-arrowhead) and processes of these cells penetrate the epidermis and are in contact with the environment (not shown here, only visible in the confocal stack). Each arrowhead labels a go-opsin+ cell. g Putative co-expression of eya with both pairs of go-opsin + cells. h Putative co-expression of myoV with both pairs of go-opsin + cells. i Putative co-expression of six1/2 with the posterior pair of go-opsin+ cells. In mid-stage trochophores (j–m), go-opsin, eya, myoV and six1/2 are probably co-expressed in both apical cells that migrated in posterior direction (arrowheads) and in both post-trochal cells that are located in the anterolateral inner mantle margin (white-lined arrows). Both apical six1/2+ cells (arrowheads) are probably different cells than the go-opsin+, eya+, myoV+ cells since they derive from a different location at earlier stage (c.f. Additional file 1: Figure S8f). See Additional file 1: Figures S2, S4, S5 and S8 for a detailed description of the expression domains. f foot pt prototroch. Scale bars: 50 µm for image of each developmental stage