Chemoreception in gastropod molluscs: Electron microscopy of putative receptor cells

Abstract
Scanning and transmission electron microscopy of the external surface of the gastropod mollusc Pleurobranchaea californica has revealed a new exteroreceptor, characterized by dense cilia (ca. 200/cell) that project from an intraepithelial soma and exhibit dilated, discoid-shaped tips. The exteroreceptor is found in high densities (up to 5000/mm2) in areas of the body determined by behavioral assay to be chemosensitive, but nowhere else, suggesting that it is a chemoreceptor.