title: Different collagen types define two types of idiopathic epiretinal membranes.
abstract: OBJECTIVE
  To identify differences in extracellular matrix contents between idiopathic epiretinal membranes (IEM) of cellophane macular reflex (CMRM) or preretinal macular fibrosis (PMFM) type.
  
  
  RESULTS
  Idiopathic epiretinal membranes were analysed by light and quantitative transmission electron microscopy, immunohistochemistry and Western blotting. Substantial differences between CMRM and PMFM were observed regarding the nature of extracellular fibrils. In CMRM the fibrils were thin, with diameters between 6 and 15 nm. Between the fibrils, aggregates of long-spacing collagen were observed. In PMFM the diameters of fibrils measured either 18-26 or 36-56 nm. Using immunogold electron microscopy, 6-15 nm fibrils in CMRM were labelled for collagen type VI, while the fibrils in PMFM remained unstained. Using Western blotting and immunohistochemistry, a strong signal for collagen type VI was observed in all CMRM, while immunoreactivity was weak or absent in PMFM. In contrast, PMFM showed immunoreactivity for collagen types I and II, which was weak or absent in CMRM. Both types of membranes showed immunoreactivity for collagen types III and IV, laminin and fibronectin with similar intensity.
  
  
  CONCLUSIONS
  The presence of high amounts of collagen type VI in CMRM and the relative absence of collagen types I and II is the major structural difference to PMFM.
authors.affiliation: Institute of Human Anatomy and Embryology, University of Regensburg, Regensburg, Germany.
authors.forename: Michaela
authors.initials: M
authors.lastname: Kritzenberger
authors.forename: Benjamin
authors.initials: B
authors.lastname: Junglas
authors.forename: Carsten
authors.initials: C
authors.lastname: Framme
authors.forename: Horst
authors.initials: H
authors.lastname: Helbig
authors.forename: Veit-Peter
authors.initials: VP
authors.lastname: Gabel
authors.forename: Rudolf
authors.initials: R
authors.lastname: Fuchshofer
authors.forename: Ernst R
authors.initials: ER
authors.lastname: Tamm
authors.forename: Jost
authors.initials: J
authors.lastname: Hillenkamp
mesh_terms: D024042:Collagen Type I / Q000378:metabolism* / Q000648:ultrastructure; D024043:Collagen Type II / Q000378:metabolism* / Q000648:ultrastructure; D024142:Collagen Type VI / Q000378:metabolism* / Q000648:ultrastructure; D019773:Epiretinal Membrane / Q000378:metabolism* / Q000473:pathology*; D005109:Extracellular Matrix / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure; D005353:Fibronectins / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D007150:Immunohistochemistry; D007797:Laminin / Q000378:metabolism / Q000648:ultrastructure; D008854:Microscopy, Electron
chemical_list: D024042:Collagen Type I; D024043:Collagen Type II; D024142:Collagen Type VI; D005353:Fibronectins; D007797:Laminin