Abstract
Objectives: :
To study heterotipy of human cornea collagen fibrils by mean of immunogold localisation.
Methods: :
Fragments of normal human cornea (spare tissue from corneal transplants) were firstly fixed in 4% paraformaldehyde and then embedded in LR White hydrophilic resin. This technique conserves ultrastructural morphology without blocking immunoreactivity and allows post–embedding immunostaining, including immunostaining of the internal portions of cross–sectioned collagen fibrils.
Results: :
Type I collagen was revealed with secondary antibody conjugated to 15 nm gold particles and type V with secondary antibody conjugated to 5 nm gold particles.
In double labelled sections, viewed under the electron microscope, we found that individual collagen fibrils were picked up by both sets of gold particles. On separate sections, immunogold labelling for type VI collagen showed particles concentrated on rare rounded aggregates about 1 mm in diameter within the stroma, while isolated particles were associated with surfaces of collagen fibrils or were present in inter–fibrillar spaces. Immunogold labelling for type III collagen revealed no systematic presence of particles.
Discussion: :
Birk et al. (1) showed heterotipy of embryonic corneal stroma of chicken being composed of type I and V collagens. This is the first morphological demonstration of the presence of heterotypic collagen fibrils composed of type I and V molecules (but not type III) in the stroma of normal human cornea.
References: :
(1)Birk D.E., J.M. Fitch, J.P.Babiarz, T.F. Linsenmayer. Collagen type I and V are present in the same fibril in the avian corneal stroma. J.Cell Biol. 106,999–1006,1988.
Keywords: cornea: basic science