Verhoeff stock solution A is one of the three components used to prepare the Verhoeff staining solution. This staining method is used in histology to visualize elastic fibers in tissue sections. Stock solution A is an alcoholic hematoxylin solution used together with ferric chloride solution (stock solution B) and potassium iodide solution (stock solution C).

To prepare the Verhoeff staining solution, the three stock solutions are mixed in a 3:2:1 ratio (stock solution A: stock solution B: stock solution C). The resulting staining mixture is then used to visualize elastic fibers in histological tissue sections. After staining, elastic fibers appear in blue-black, while collagen fibers and cell structures are shown in other colors.