Immunogold localization of extracellular matrix molecules in Bruch's membrane of the rat

The distribution of extracellular matrix molecules in Bruch's membrane of the rat was studied by a post-embedding immunogold labeling method. These molecules included laminin, types I, III and IV collagen, fibronectin and heparan sulfate proteoglycan. Laminin and type IV collagen were localized in the basal lamina of the pigment epithelium and choriocapillaris; types I and III collagen, to the inner and outer collagenous zones; fibronectin, to the elastic layer; heparan sulfate proteoglycan was found diffusely throughout the entire Bruch's membrane. These results not only agree with previous biochemical and immunofluorescence studies of these molecules in Bruch's membrane of other species but also provide a more precise localization of these molecules in the various layers of Bruch's membrane.