Figure 4

HasSom expression correlates with shell pigmentation. (a) Juvenile H. asinina shell prior to whole mount in situ hybridization against HasSom. (b) The same shell partially decalcified. (c) Dorsal view of shell-less juvenile illustrating HasSom expression (arrows). (d) Dissected portion of the mantle (corresponding to the boxed region in c). Coloured lines indicate corresponding regions of the shell and periostracum in (a) and (b). A cross section (insert) shows HasSom expression restricted to the dorsal surface of the outer fold (white arrowhead), and to the dorsal surface of the periostracal groove (black arrowhead).