| This study expands the reptilian inner ear database with information derived from scanning electron micrographs of the red-eared turtle saccular macula. Throughout this vestibular sensor three regions were present based on hair cell bundle morphology: striola, extrastriola and periphery. The overlying, otoconial membrane and mass displayed a margin with three zones that corresponded to these underlying regions. Striolar stereovillar bundles were short, wide, unimodal in profile and stereometrically tight. This morphology suggests that the striola may be dynamically sensitive to large acceleratory forces. Extrastriolar stereovillar bundles were taller, narrower, bimodal in profile and stereometrically loose. This morphology suggests that the extrastriola may be dynamically sensitive to small acceleratory forces. Unlike the others, peripheral bundles had a tall, bulbed kinocilium that appeared to be closely linked to the otoconial membrane. Thus, the periphery may function as a tonic sensor, sensitive to positional head changes. |
