VIII GRANULATION TISSUE CHEMISTRY 695 



creased in areas where metachromasia is greatest, although this finding has not 

 always been substantiated by others (Bunting and White, 1950; Holczinger and 

 Devenyi, 1955; Taylor and Saunders, 1957). Asboe-Hansen (1950a, b, 1954) 

 found a definite relationship between number of these cells and amount of hyal- 

 uronic acid present in connective tissue, and mast cells seem to be present in large 

 numbers wherever new formation of connective tissue takes place. 



Wichmann (1955) made a detailed quantitative study of mast cells during 

 wound healing in rats and found a decrease for the first 24 h. ; by the second day a 

 definite rise was apparent, which reached a peak on the eighth to tenth day and 

 gradually returned to normal by the 32nd day. Mast cells release a large portion of 

 their cytoplasmic granules whenever the water content of the surrounding tissue 

 is increased (Benditt et al., 1954; Fawcett, 1955). Tyrode solution or physiological 

 saline injected subcutaneously in hamster cheek pouches results in degranulation 

 and release of mucopolysaccharide material to the intercellular substance 

 (Wegelins and Asboe-Hansen, 1956). In wounds there is also an increased water 

 content, this remains until the loth to 15th day, probably as an osmotic phenome- 

 non, which further supports the idea that wound edema may be the factor causing 

 mast cells to release their mucopolysaccharides. Asboe-Hansen has mentioned that 

 the normal perivascular accumulation of mast cells is consistent with this view. He 

 thinks that some hormonal influence causes mast cells to secrete the mesenchymal 

 mucopolysaccharide, hyaluronic acid, via sulfonic precursors related to heparin. 

 If such is the case, the secreted polysaccharide changes form because neither the 

 mast cell metachromasia nor that of the granulation tissue is blocked by testicular 

 hyaluronidase. Wichmann (1955), on the other hand, believes that the function of 

 mast cells is probably to prevent clotting in newly formed capillaries by releasing 

 heparin. 



The majority of investigators Tustanovsky, 1947; Orekhovich et al., 1948; 

 Klemperer, 1952; Bunting and Bunting, 1953; Glucksman et al., 1956) agree with 

 Meyer (1947) that fibroblasts rather than mast cells produce the mucopolysaccha- 

 rides. Taylor and Saunders (1957) claim this to be a function of immature 

 fibroblasts, occurring for only a relatively short period of their normal physiologic 

 activity. Curran and Kennedy (1955) recently upheld this idea by finding that the 

 -^^S uptake is high in fibroblasts surrounding a quartz focus. They believe it is 

 fixed to the sulfated mucopolysaccharides, since mammals are unable to incorpo- 

 rate sulfate ions into sulfur-containing amino acids and the sulfur of cystine is 

 formed by intestinal flora. In vitro experiments by Grossfeld et al., (1955) have 

 shown that either the subcutaneous tissue of rats or human embryonic skin, both 

 of which contain many fibroblasts, can form a mucin clot. Testicular or bacterial 

 hyaluronidase inhibits this clot formation, indicating its mucopolysaccharide 

 nature. 



The mucopolysaccharide content of tissues may be studied by several methods. 

 Histochemically these include metachromatic staining by Toluidine blue and other 

 basic dyes; oxidation such as the P.A.S. method; iron absorption techniques, e.g. 

 Hale's (1946) method; and Alcian blue staining^ Hexosamine determination, 

 according to the method of Elson and Morgan (1933) as modified by Blix (1948), is a 

 satisfactory biochemical method for quantitating the mucopolysaccharide content. 



Lileralure p. 703 



