Figure 4

Musculature and innervation of the mantle. A. Localisation of actin filaments in the juvenile mantle revealed by phallacidin staining (green). Dorsal view of left (upper) and right (lower) mantle lobes, anterior is to the right. The majority of filaments lie perpendicular to the mantle edge (arrows), however some longitudinal fibres can be seen (double arrowhead). Pigment autofluorescence is visible within some tubules (red), nuclei are stained with DAPI (blue). B. Innervation of the juvenile mantle revealed by anti-acetylated tubulin immunoreactivity (green), orientation as in A. Nerve fibres become more dense in the distal edge of the mantle, in the proximity of the tubules and periostracal groove (arrows). Cilia within the groove are also labelled (arrowheads), as are individual ciliated cells (*). C. Higher magnification of A, showing muscle fibres (green) running between pigment-filled tubules (red). DAPI-stained cell nuclei are in blue. Scale bar = 15 μm. D. Higher magnification of B, showing nerve fibres extending past the tubular zone into the inner fold (arrow). Cilia within the periostracal groove (arrowhead) and a ciliated cell (*) are also visible. Scale bar = 10 μm. E. Distribution of the neuropeptide FMRF-amide revealed by immunostaining (green). Dorsal view of a similar region to D, the opening to the periostracal groove is indicated by an arrowhead. Staining reveals increased complexity of neuronal structures than that visualised by tubulin staining (arrow). Scale bar = 30 μm. The bottom of the image is towards the mantle edge in C, D and E.