Differential staining of collagen types in paraffin sections: A color change in degraded forms

The Herovici combination of picro methyl blue or aniline blue and picro acid fuchsin in proper proportion colors mature dense collagen red while reticulum and newly formed collagen are blue. Fetal collagen, wound healing collagen, subepidermal finely fibrillar collagen, deteriorating collagen in and over arterio-sclerotic lesions tend to take the blue stain. Arterial adventitial, deep dermal gastric submucosal collagens are red.