Morphology of the basilar papilla of the bobtail lizard Tiliqua rugosa.

The morphology of the basilar papilla of the bobtail lizard was investigated with standard light- and scanning-electron-microscopical methods. The papilla can be subdivided into two parts: a small apical segment which is rather uniform in structure and a long basal segment which displays various systematic changes along its length, for example in the density of the hair cells, the height and shape of the hair-cell stereovillar bundles, the number of stereovilli per bundle and the size of the tectorial structure. In addition, the tectorial structures overlying the two segments are very different in size and morphology. Both tectorial structures are probably sensitive to changes in their ionic environment. The possible functional implications of the papillar morphology described here are discussed with respect to a model of frequency tuning in the bobtail lizard.