THE MAST CELLS 



Histological examination showed that the pyloric portion of the stomach 

 of the rat is not especially rich in mast cells. A few are present in the submucosa, 

 about the level at which the mucosa can be scraped off; but the mucosa itself 

 is almost devoid of mast cells. 



Further attempts to divide the wall of the rat's stomach into multiple slices 

 parallel to the surface were not very successful. However, the pyloric portion of 





Fig. 51 



Paraffin section through mucosa and submucosa of pyloric portion of hog stomach (the section is 



lying on its side to correspond with the next figure). The numerous dark spots in the submucosa 



are mast cells. A few mast cells occur in the deeper mucosa between the mucous glands, which 



also stain metachromatically with toluidine blue ( ■ 44). 



the stomach of the pig is not only thick; it also contains very many mast cells 

 in the loose connective tissue on which the mucosa rests. We therefore pre- 

 pared histamine- and mast-cell ' profiles ' of the pyloric wall of hog stomach 

 (Riley and West, 1956a). 



Figure 51 shows, at low magnification, a vertical section through the 

 mucosa and submucosa of the pyloric portion of hog stomach, fixed in the fluid 

 recommended for mast cells by Constantinides (1953) and stained with 0-1 per 

 cent aqueous toluidine blue. Even at this magnification the dense accumulation 

 of mast cells in the submucosa is clearly visible. Under high power these cells 

 are seen to contain granules which stain metachromatically (purple to red)* 



134 





