MAST CELLS IN CATTLE AND RAT 



centre of which a small pyknotic nucleus can occasionally be seen. These 

 degenerate cells are usually situated at some distance from the nearest vessel 

 (Figs. 13, 14). 



Discussion 



Examination of stained tissue spreads of subcutaneous connective tissue, 

 mesentery, omentum and the uterine fringes from female rats leaves no doubt 



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Fig. 1! 



Whole mount preparation, outer skin and subcutis, of rat ear. Numerous mast cells around 

 hair follicles and in loose connective tissue, as in mouse ear (fig. 56). Toluidine blue ( : 128). 



as to the close association of the mast cells with the blood vessels in this species. 

 On the other hand, it does call in question certain views which are widely held 

 regarding the exact relationship of the mast cells to the vessels, and hence casts 

 doubt upon the deductions that have been made from such observations. 



In his book on Heparin, Jorpes (1946, p. 64) quotes Quensel (1933) that 

 mast cells are situated predominantly around 'thin-walled blood vessels which 

 lack muscle coats', thereby strengthening his belief that the function of the 

 mast cell is to produce an anticoagulant which is poured into the blood. His 

 accompanying illustrations do not entirely support this view. In his Figures 

 \a-\b (facing p. 60) the transition from Type I to Type II mast cells is clearly 

 seen — small spindle-shaped orthochromatic cells in the vessel wall developing 



57 



