Post-larval expression of Gva-Gsx. (A) Medial longitudinal section through the radula of a hatched juvenile stained with Toluidine Blue. (B) Paired odontoblastic cushions at the base of the radula sac where radula teeth are formed. The staining is Toluidine Blue. (C-E) Gva-Gsx expression is observed in odontoblastic cushions of the hatchling. The black rectangular area marked on (C) is demonstrated in higher magnification in (D). The gradient of Gva-Gsx expression in odontophores and odontoblast is shown in (E). bc buccal cavity, cf ctenidial filaments, eso esophagus, frt forming radula teeth, ie inferior epithelium, j jaw, mf mantle fold, mo mouth opening, oc odontoblastic cushions, od odontoblasts, odc odontoblastic cartilage, op odontophores, op operculum, pf pedal folds, rm radula membrane, rn radula nerve, rt radula teeth, sc separating cells, sm shell matrix, tsm tensor muscle.