Figure 6

Ciliary opsin positive cells in decalcified arms of Amphiura filiformis, detected by Confocal laser scanning microscopy. Double immunolocalisation of c-opsin (red) and acetylated alpha-tubulin (green). A. Partially inverted transmission picture of an arm showing c-opsin positive cells/photoreceptor cells (cop + PRC) in the spines (sp). B. c-opsin proteins seem to be localised in the inner portion of the spines. C. Dense nerve tracts are present at the basis of the spines. D. Nerve tracts partially also run through an internal portion of the spines. Tube feet (tf) show no c-opsin positive cells. E. High magnification reveals connection of the c-opsin positive cells to the nerve tracts (ntr). F. Transmission view of a spine showing the internal c-opsin positive cells and the dark pigment (pig) at the spine base. Scale bars in A-D: 100 μm, E: 20 μm, F: 50 μm.