Micrographs showing the healthy and overgrown gingivae. (a-b) Hematoxylin and eosin staining reveals the morphological structure of the epithelium and of the connective tissue. (c-d) Sirius Red staining stains in red the collagen fibers of the connective tissue. (e-f) Polarized light performed on Sirius Red-stained samples shows birefringence relative to collagen fiber arrangement and maturation. Original magnification: 20x.