Histologic and statistical studies on hyalin bodies in the human endolymphatic sac

Hyalin bodies are amorphous, eosinophilic masses that protrude from the subepithelial connective tissue into the lumen of the endolymphatic sac. In this study, hyalin bodies were analyzed in two groups of temporal bones: normal bones and bones with cochlear otosclerosis. The results revealed that bones with cochlear otosclerosis had significantly more and larger hyalin bodies that did normal bones. In addition, the hyalin bodies in cochlear otosclerosis were denser and associated with more edema and loose connective tissue in the surrounding areas. Foamy macrophages, concentric calcific structures, and bony ingrowth were frequent features of the hyalin bodies in the cochlear otosclerosis. Our current hypothesis is that these hyalin bodies are repository of membranous cellular debris phagocytized by the macrophages. If this is true, the hyalin bodies may further support the proposed resorptive and phagocytic functions of the endolymphatic sac and the enzymatic concept in cochlear otosclerosis.