Oxalic acid, 1% solution is a component of many special staining kits, such as Paraldehyde Fuchsin kit, Hematoxylin P.T.A. kit, Masson Fontana kit and Reticulin Contrast kit. Paraldehyde Fuchsin kit is used for visualization and detecting pathologic changes in elastic fibers, such as elastic tissue atrophy, loss or thinning of elastic tissue caused by atherosclerotic changes or vascular diseases. It is also used for staining pancreatic beta cells, mastocyte granules, mucin, cartilage, argentaffin granules and sperm acrosomes. Hematoxylin P.T.A. kit is used for better visualization of central nervous system, fibrin, but also primarily for differentiating between smooth and skeletal muscle tissue. Masson Fontana kit is used in a specific method for proving melanin and argentaffin granules in histology sections, based on reduction of silver nitrate to elemental silver. Reticulin Contrast kit is used for identification and easier visualization of argentaffin reticular fibers in connective tissue.