RS-like immunoreactivity in the hyponeural part of the radial nerve and in the nerve ring. Dashed line shows the basal border of the hyponeural (hn) part of the radial nerve cord. A. Peroxidase-antiperoxidase immunohistochemistry with the RS-K10 antiserum on a transverse section of the radial nerve cord of E. fraudatrix showing immunopositive cells (arrowheads) in the hyponeural neuroepithelium (hn) and in the non-neural roof epithelium (re). Note that there is no immunoreactive material neither on the apical surfaces of the epithelia, nor in the lumen of the hyponeural canal (hc). B. Dotted labelling (green) in the lateral region of the hyponeural neuroepithelium (asterisk) of H. glaberrima visualized by immunostaning with the AFRU antiserum. Nuclei are stained with Hoechst (blue). C. Sagittal section through the pharyngeal bulb (the oral end of the animal is to the right) of H. glaberrima showing the intense AFRU-positive immunoreactivity (arrows) associated with the apical surface of the ectoneural neuroepithelium (en) and with the epineural roof epithelium. D. High magnification view of a region of the nerve ring with a locally dilated lumen of the circular epineural canal (cec) showing the AFRU-positive labelling (green) in the apical region of the ectoneural neuroepithelium and in the epineural roof epithleium (re). Nuclei are stained with Hoechst (blue). Scale bars = 10 μm in (A), 50 μm in (B), 15 μm in (C), 20 μm in (D).