title: The Ultrastructural Localization of Type II, IV, and VI Collagens at the Vitreoretinal Interface.
abstract: BACKGROUND
  The vitreoretinal interface is the border of the cortical vitreous and the inner surface of the retina. The adhesion of the cortical vitreous to the ILM, namely vitreoretinal adhesion, involves a series of complex molecular adhesion mechanisms and has been considered as an important pathogenic factor in many vitreoretinal diseases. The presence of type VI collagen at the vitreoretinal interface and its possible interaction with collagens and glycoproteins indicates that type VI collagen may contribute to the vitreoretinal adhesion.
  
  
  OBJECTIVE
  To clarify the ultrastructural location of type VI collagen and its relationship to type II and IV collagens at the vitreoretinal interface.
  
  
  METHODS
  The ultrastructural localization of type II, IV and VI collagens in the adult human vitreoretinal interface of five donor eyes was evaluated by transmission electron microscopy using immunogold labeling.
  
  
  RESULTS
  In the pre-equatorial region, we observed densely packed vitreous lamellae with a partly intraretinal course containing type II and VI collagens, reticular structures containing type IV and VI collagens and a thin inner limiting membrane (ILM) containing type IV and VI collagens in a linear distribution pattern. From the anterior to the posterior retina, the linear pattern of type IV and VI collagen labeling gradually became more diffusely present throughout the entire thickness of the ILM.
  
  
  CONCLUSIONS
  The presence of type VI collagen in vitreous lamellae penetrating the ILM into the superficial retina suggests that type VI collagen may be involved in the organization of vitreous fibers into lamellae and in the adhesion of the vitreous fibers to the retina. The close relation of type VI to type IV collagen in the ILM suggests that type VI collagen is an important collagen type in the ILM. The topographic variations of type IV and VI collagens in the different regions of the ILM suggest a regional heterogeneity of the ILM. The reticular labeling pattern of type IV and VI collagens observed in the anterior vitreous are highly similar to labeling patterns of blood vessel walls. In the anterior vitreous, they may represent remnants of the regressed embryonic hyaloid blood vessel system. Their presence is in support of the theory on interactive remodeling of the developing vitreous as opposed to the main stream theory of displacement and compression of the primary by the secondary vitreous.
authors.affiliation: Department of Ophthalmology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands; W.J. Kolff Institute, Graduate School of Medical Sciences, University of Groningen, Groningen, the Netherlands; Tianjin Medical University Eye Hospital, Tianjin Medical University, Tianjin, China, Fu Kang Street 251, Nan Kai District, Tianjin, 300384, China.
authors.forename: Shao Chong
authors.initials: SC
authors.lastname: Bu
authors.affiliation: Department of Biomedical Engineering, FB40, University of Groningen, University Medical Center Groningen, A. Deusinglaan 1, building 3215, FB40, 9713 AV, Groningen, The Netherlands; W.J. Kolff Institute, Graduate School of Medical Sciences, University of Groningen, Groningen, the Netherlands.
authors.forename: Roel
authors.initials: R
authors.lastname: Kuijer
authors.affiliation: Department of Ophthalmology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands; W.J. Kolff Institute, Graduate School of Medical Sciences, University of Groningen, Groningen, the Netherlands.
authors.forename: Roelofje J
authors.initials: RJ
authors.lastname: van der Worp
authors.affiliation: Tianjin Medical University Eye Hospital, Tianjin Medical University, Tianjin, China, Fu Kang Street 251, Nan Kai District, Tianjin, 300384, China.
authors.forename: Xiao Rong
authors.initials: XR
authors.lastname: Li
authors.affiliation: Department of Ophthalmology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands; W.J. Kolff Institute, Graduate School of Medical Sciences, University of Groningen, Groningen, the Netherlands.
authors.forename: Johanna M M
authors.initials: JM
authors.lastname: Hooymans
authors.affiliation: Department of Ophthalmology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands; W.J. Kolff Institute, Graduate School of Medical Sciences, University of Groningen, Groningen, the Netherlands.
authors.forename: Leonoor I
authors.initials: LI
authors.lastname: Los
mesh_terms: D000368:Aged; D003094:Collagen / Q000648:ultrastructure*; D006801:Humans; D046529:Microscopy, Electron, Transmission; D008875:Middle Aged; D012160:Retina / Q000648:ultrastructure*; D014822:Vitreous Body / Q000648:ultrastructure*
chemical_list: D003094:Collagen