Papillary morphology of the tongue of the American chameleon: Anolis carolinensis

Abstract

Based on regional differences in surface morphology, the dorsum of the tongue of Anolis carolinensis can be subdivided into four distinct zones. The first quarter of the tongue is relatively smooth, whereas the second and fourth quarters are festooned with closely packed cylindriform papillae, which are covered by typical parakeratotic stratified squamous epithelium. The third quarter of the tongue is covered by papillae of novel morphology that we have named “plumose papillae.” These are composed of a slender connective tissue core covered by stratified squamous epithelium from whose surface numerous elongated cells radiate. These “plume cells” are about 30–40 μm long and have an extremely irregular nucleus in their expanded terminus. Their stalks are affixed by desmosomes to the deeper cells of the epithelium, and their free surfaces are covered by intricately patterned microplications. Their cytosol contains a dense web of 100‐Å cytofilaments that may be involved in maintaining the peculiar morphology of the cells. Regardless of type, all lingual papillae of A. carolinensis contain a single longitudinally oriented skeletal muscle fiber that originates from the underlying lingual muscles, raising the possibility that the papillae can be moved at will. The plumose papillae and their retinue of plume cells are unique morphological structures that may be important in mastication and deglutition of food.