Hematoxylin acc. to Weigert is used in combination with various special (trichrome) stains. Because of its resistance to acidic solutions, it retains the dye and stains nuclear membranes. Unlike the standard hematoxylins used in histology, such as hematoxylins acc. to Harris, Mayer, Mayer-Lillie, and Gill, Hematoxylin acc. to Weigert contains ferric ions that create resistance to acidic solutions and sudden pH value changes. Hematoxylin acc. to Weigert is most commonly used in the following trichrome methods: A.F.O.G., Gomori Trichrome, Masson-Goldner Trichrome, Masson Trichrome, Van Gieson Trichrome, Elastica-Van Gieson and Weigert-Van Gieson. Most of those methods are used for staining muscle and connective fibers.