THE MAST CELLS 



well-granulated mast cells which stained brilliantly with the Leishman-Giemsa 

 and aldehyde-fuchsin methods. The granules also stained positively with the 

 periodic acid-Schiff method, indicating perhaps that here the heparin is not 

 fully sulphated (Jorpes, Werner and Aberg, 1948). Mast cells were numerous 

 in the enlarged nodes and spleen and were present as islets of cells in the liver 

 parenchyma and as extensions along the portal tracts. The histamine content 

 of the primary tumour was very high indeed — 1,250 \±g. g. Curiously enough, 

 the heparin content (measured as anticoagulant) was low — only 8-0 i.u./g. 



The second case was that of a five-year-old female cat with numerous small 

 skin nodules, some of which had undergone ulceration. The condition had 

 been present for two months and had failed to respond to a course of strepto- 

 mycin. Accordingly, three nodules were removed, one for histological 

 examination and the others for pharmacological assay, though two days 

 elapsed before they were placed in the appropriate fluids. The skin nodule 

 proved to be a non-encapsulated aggregation of mast cells in the upper dermis: 

 its histamine content (after two days) being 32 [xg./g. Again the heparin value 

 was low, only 6-5 i.u./g. Later the animal was destroyed and the carcass sent 

 for post-mortem examination, though there was again an inevitable delay of 

 two days in transit, the specimen having been sent from a veterinary practitioner 

 in Lancashire. At autopsy it was found that many of the lymph nodes draining 

 the skin were enlarged and that there was gross enlargement of the spleen. The 

 abdominal lymph nodes and bone marrow appeared normal. Microscopically 

 it was found that here, as in the first case, the nodes draining the involved skin 

 were infiltrated with well-granulated, metachromatic mast cells and that in 

 the skin itself the nodules were very numerous indeed. The spleen was very 

 heavily infiltrated and there was widespread periportal infiltration of mast cells 

 in the liver. In contrast, the lung contained only a few additional mast cells: 

 kidney and bone marrow were normal. The histamine and heparin values of 

 various tissues in this case and the extent to which they diverge from normal 

 values are set out in Table XI. 



Table XI 



Histamine and heparin values in tissues obtained two days post- 

 mortem from a cat with multiple mast-cell nodules in the skin. 

 (Figures in brackets indicate relationship to normal values) 



