THE MAST CELLS 





/ 



Fig. 63 



High power view of the intense mast-celi reaction which has developed around a focus 

 of precancerous epithelial cells situated near the edge of a large papilloma three 

 months after painting the mouse skin with a potent carcinogen. Following fixation 

 of the tissue in formaldehyde, such mast cells may show a golden-brown fluorescence 

 in ultra-violet light. Toluidine blue ( 550). 



56 



