A morphological study of human vestibular sensory epithelia.

Surface preparations were made of the vestibular sense organs of humans from membranous labyrinths removed within ten hours of death. Total sensory cell counts and surface area measurements were made from composite photographic reconstructions. The general topographical and cytoarchitectural arrangements were found to be similar to those previously described for the guinea pig and squirrel monkey. The surface areas and sensory cell populations of the human cristae were only slightly greater than those recorded for these animals; however, the figures for the human maculae were twofold to fourfold greater. It seems possible that this exceptional enlargement of the sensory epithelia of the static labyrinth is in response to a physiological need generated by the evolutionary transition of primates from the quadruped to the biped stance.