has part has part has_part characteristic of has modifier vestibular dark cell abnormal inner ear vestibule morphology abnormal vestibular dark cell morphology any structural anomaly in the nonsensory epithelial cells located above the vestibular melanocytes and adjacent to the sensory structures in the utricle and in the ampullae at the ends of each of the semicircular canals; these cells provide and maintain the high potassium ionic environment within the vestibular labyrinth and are therefore homologous to the marginal cells of the stria vascularis; they are joined to each other by tight junctions and provide a barrier between endolymph and perilymph MPheno.ontology MP:0004775 morphology abnormal