ClCdx expression in the juvenile nervous system of C. longifissura. (a) Dorsal view ClCdx expression in the juvenile head region. (b) Infra red-reflection microscopy of deep layers of the anterior part of the juvenile seen in (a). The outline of the animal is indicated with the dotted line. The white arrowheads indicate expression in the connectives extending to the anterior neural region. ey = eye, st = statocyst. (c) Frontal view of the image stack of (b). (d) Ventral view of the ectodermal expression of ClCdx. Expression flanks the latero-ventral nerve chords. The black arrowhead indicated the ectodermal expression in the region of the future gonopore. Mouth denoted by dotted circle (e) Dorsal view of a juvenile stained with anti-tyrosinated-tubulin antibody (red) showing a subset of the anterior commissures and connectives leading to the sensory cells surrounding the tip of the animal. (f) Nile-Blue stained histological cross section through the area anterior to the mouth, where ClCdx is expressed. White arrowheads point to nerve strands surrounding the gland cells of the frontal organ (fo) and extending nervous tissue in the ventral fold.