title: Macromolecular organization and fine structure of the human basilar membrane - RELEVANCE for cochlear implantation.
abstract: BACKGROUND
  Cochlear micromechanics and frequency tuning depend on the macromolecular organization of the basilar membrane (BM), which is still unclear in man. Novel techniques in cochlear implantation (CI) motivate further analyses of the BM.
  
  
  METHODS
  Normal cochleae from patients undergoing removal of life-threatening petro-clival meningioma and an autopsy specimen from a normal human were used. Laser-confocal microscopy, high resolution scanning (SEM) and transmission electron microscopy (TEM) were carried out in combination. In addition, one human temporal bone was decellularized and investigated by SEM.
  
  
  RESULTS
  The human BM consisted in four separate layers: (1) epithelial basement membrane positive for laminin-β2 and collagen IV, (2) BM "proper" composed of radial fibers expressing collagen II and XI, (3) layer of collagen IV and (4) tympanic covering layer (TCL) expressing collagen IV, fibronectin and integrin. BM thickness varied both radially and longitudinally (mean 0.55-1.16 μm). BM was thinnest near the OHC region and laterally.
  
  
  CONCLUSIONS
  There are several important similarities and differences between the morphology of the BM in humans and animals. Unlike in animals, it does not contain a distinct pars tecta (arcuate) and pectinata. Its width increases and thickness decreases as it travels apically in the cochlea. Findings show that the human BM is thinnest and probably most vibration-sensitive at the outer pillar feet/Deiter cells at the OHCs. The inner pillar and IHCs seem situated on a fairly rigid part of the BM. The gradient design of the BM suggests that its vulnerability increases apical wards when performing hearing preservation CI surgery.
authors: Department of Surgical Sciences, Head and Neck Surgery, section of Otolaryngology, Uppsala University Hospital, 751 85, Uppsala, Sweden, lwoo24@gmail.com.
authors: Wei
authors: W
authors: Liu
authors: Francesca
authors: F
authors: Atturo
authors: Robair
authors: R
authors: Aldaya
authors: Peter
authors: P
authors: Santi
authors: Sebahattin
authors: S
authors: Cureoglu
authors: Sabrina
authors: S
authors: Obwegeser
authors: Rudolf
authors: R
authors: Glueckert
authors: Kristian
authors: K
authors: Pfaller
authors: Annelies
authors: A
authors: Schrott-Fischer
authors: Helge
authors: H
authors: Rask-Andersen
mesh_terms: D001489:Basilar Membrane / Q000648:ultrastructure*; D019929:Cochlear Implantation; D006801:Humans; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission