[Scanning electron microscopic observation of human vestibular sensory epithelia]

Three-dimensional structures of human vestibular sensory epithelia were studied under scanning electron microscope. The saccular macula showed an "L" pattern and increased in thickness near the striola. The utricular macula appeared like an open shell. Flask and test-tube shaped hair cells were identified as type-I and type-II sensory cells respectively. Stereocilia were arranged in a step like progression; the kinocilium was near the longest stereocilium and looked more flexible than stereocilia. The tallest stereocilia and kinocilia faced away from the striola toward the periphery in the macula sacculi, and toward each other along the striola in the utricular maculae. Polarization directed to the utricle in the lateral crista, and away from the utricle in the anterior and posterior cristae. Otoconia varied in size and shaped like crystals with pyramidal ends.