Heparin and Histamine in Mast-Cell Tumours from Dogs

THE granular basophil cell of the tissues, the mast cell, has for long been thought to be the source of heparin¹. Recently, it has been shown that the mast cell is also rich in histamine, a suggestion first made on histological grounds² and afterwards confirmed by the finding of a strong positive correlation for mast cells and histamine in a wide variety of normal and pathological tissues³. However, up to the present, the only comparative study of mast cells for heparin and histamine in the same starting material has been carried out on normal ox lung, in which the pleura especially yielded high values for all three⁴. It is thus of some interest that we have recently obtained six cases of subcutaneous mast cell tumour from dogs for estimation of their heparin and histamine contents.