Simultaneous demonstration of mast cells and plasma cells.

In order to obtain a compound stain to differentiate between mast and plasma cells, it was necessary to find dyes which provided a distinct colour contrast between the two types of cell. The aqueous acetic Alcian blue method (McManus and Mowry, 1960) stained mast cells, but also other tissue elements. Using Alcian blue at a pH less than 10 (Johnson and Helwig, 1963) the mast cells stained brilliant turquoise-blue, with pale turquoise-blue background staining of connective tissue mucin. An alcoholic solution of Alcian blue at pH 0 5 was found to give the