The ultrastructure of the endolymphatic sac in Meniere's disease.

Biopsies of the endolymphatic sac were performed in 6 patients undergoing endolymphatic sac decompression and/or drainage procedures. Electron microscopy revealed extensive subendothelial fibrosis with loss of vascularity, heavy deposition of collagen and flattening of luminal cells. In patients with long-standing disease, complete obliteration of the endolymphatic sac lumen appeared to occur. There was poor correlation between the surgeon's ability to identify the lumen of the endolymphatic sac and its presence in the biopsy specimen.