Mature hematoxylin reacts with tungsten to form blue sediment which strongly combines with tissue. Reddish brown portion is stained by Phosphotungstic Acid. The nucleolus, which is made up of acid materials, has a strong affinity for alkaline stain (Hematoxylin) while the cytoplasm, made up of alkaline materials, binds favorably to acid stain (Eosin). Therefore, in the presence of the H-E stain, nucleolus will be stained bright indigo blue by hematoxylin; cytoplasm, stroma, muscle fiber and collagen fiber will be varying shades of pink; and erythrocyte will be salmon pink.