On the ultrastructure of the abdominal sense organ of the giant scallop, Placopecten magellanicus (gmelin).

The abdominal sense organ of the giant scallop, Placopecten magellanicus, is composed of two cell types. The presumed receptor cells bear a single cilium 60 to 70 micrometer in length. The microvilli at the apices of these cells may also be modified into microvillous whorls. From eight to twelve ciliated cells are associated with a single mucous cell. The mucous cells have a much greater diameter than the ciliated cells and contain many electron-dense mucous granules. No function has yet been determined for the ciliated cells, although a number of theories are presented.