THE MAST CELLS 



It has been known since the time of Ehrlich and Westphal that the mast 

 cells in certain species are extremely susceptible to the action of water; hence 

 water is a histamine-liberator for these species. When the tissues are stored 

 under more physiological conditions, as in balanced salt solution, the mast 

 cells survive longer and the histamine value of the tissue is sustained. This is 

 illustrated in Table XX in which histamine values were recorded for strips of 

 fresh sheep liver capsule, taken from the same animal, and immersed for one 

 hour in water, normal saline or a dilute solution of the histamine-liberator 

 D-tubocurarine. 



Table XX 



Effect of water, sodium chloride solution (0 9 per cent 

 vv/v), and solution of D-tubocurarine (01 per cent wjv) 

 on the histamine content ([ig./g. tissue) and mast-cell 

 content of sheep-liver capsule. Immersion time, 1 /;/'. 

 at room temperature 



The mast granules in excised tissues of the rat are comparatively resistant 

 to osmotic disruption by water (Paff and Mergenthaler, 1955). Nevertheless, 

 as Fawcett (1954) has shown, the repeated intraperitoneal injection of 

 comparatively large volumes of water into the living rat removes, almost 

 selectively, the mast cells from the peritoneum; meanwhile the histamine is 

 released into the water and can be assayed. The corollary experiment can then 

 be performed: a subsequent injection of compound 48 80 fails to release more 

 histamine, its target, the mast cells, having already been destroyed. 



The effects of water on the mast cells can be conveniently followed under 

 the microscope. If a fresh tissue spread containing mast cells, such as a piece 

 of ox peritoneum, is placed on a warm slide and covered with a drop of water 

 containing a little dilute toluidine blue, the whole interaction of water with the 

 mast cell can be observed. At first the dye is concentrated exclusively in the 

 granules, though not all the granules stain simultaneously, even in the same 

 cell. As staining takes place the colour of the dye changes from blue to purple 

 or even to red (metachromasia). It is a little difficult to reconcile this observa- 

 tion with the view still held by Sylven (1957) that the metachromatic material 

 is normally located in the intergranular cytoplasm and that its presence in, or 

 on, the granules is an artefact (Julen et al, 1949). It has long been known that 

 scattered granules still stain metachromatically. Next, both cell and granules 



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