A = Mild oral epithelial dysplasia (OED) lesion with increased of type I collagen throughout the extracellular matrix (ECM).
B = Basement membrane thickening due to collagen deposition in mild OED (arrowheads).
C = Severe OED/high-risk oral lesion with lamina propria preserving the feature of loose connective
D = Well differentiated OSCC exhibiting increased expression of type I collagen over the stroma.
E = Moderately differentiated OSCC with a discrete collagen expression on ECM.
F = Epithelium-connective tissue interface of moderately differentiated OSCC with diffuse matrix and inflammatory infiltrate.
A, B, C, D, E, F = type I collagen was analysed by immunohistochemistry, scale bar = 20 μm.