Immuno-scanning electron microscopy of collagen types I and III in human vocal fold lamina propria

This study was undertaken to identify the types of collagen fibrils in the extracellular matrix of the human vocal fold lamina propria.

Human vocal folds were obtained from 3 autopsy cases less than 65 years of age. The vocal fold specimens were labeled by primary antibodies of anti-type I and anti-type III collagens, and then by secondary antibody conjugated with 15 nm colloidal gold. The specimens were observed with a scanning electron microscope. Secondary electron imaging and backscatter electron imaging of high-resolution field emission scanning electron microscopy were used to detect gold particles indicating immunolabeling.

Type III collagen-labeling gold particles were abundant on the fibrils constructing collagenous fibers, whereas type I collagen-labeling gold particles were sparsely present on fibrils in collagenous fibers. A few reticular fibers were labeled by both collagen type I and collagen type III.

The results suggest that collagen type I coexists with collagen type III in fibrils of both collagenous fibers and reticular fibers.