VIII GRANULATION TISSUE CHEMISTRY 697 



McManus, 1957) ; however, if the reaction is blocked with testicular hyaluronidase, 

 they become positive (Hayashi et al., 1955). The P.A.S. reaction depends upon 

 free i, 2 glycol groups; if these are blocked by sulfation, the reaction becomes 

 negative and metachromasia is positive (Kramer and Windrum, 1954). Whether 

 metachromasia is dependent upon the state of polymerization (Lennox et al., 

 1952), the degree of sulfation, number and dissociation of the attached acidic 

 radicals, or the solubility of the dye-substrate complex is not established (Walton 

 and Ricketts, 1954). Of interest is the fact that not only does the metachromatic 

 reaction of Toluidine blue increase in granulation tissue but also the uptake of 

 the dye itself (Balazs and Holmgren, 1950). This uptake parallels that of meta- 

 chromasia and is most probably due to the basic dye's becoming attached to 

 acid (negative) groups such as high-molecular polysaccharides. Thus histochemical 

 evidence strongly indicates that the mucopolysaccharide content of granulation 

 tissue is elevated early in the course of wound healing and subsequently returns to 

 normal. Direct estimations of hexosamine have verified this (Dunphy and Udupa, 

 1955; Kodicek and Loewi, 1955). Furthermore, there appears to be a qualitative 

 change in the mucopolysaccharides during healing. 



Recently this relationship between mucopolysaccharides and collagen content 

 of wounds has been correlated by Dunphy and Udupa (1955). They used hexos- 

 amine and hydroxyproline determinations along with various histochemica 

 methods. In sutured rat wounds the mucopolysaccharide content rose rapidly, and 

 after the third day it gradually fell to normal levels. The curve of collagen content 

 did not rise until the polysaccharide level commenced to fall and continued 

 through the 12th- 14th day, at which time it began to form a plateau. Aber- 

 crombie and James (1957) investigated the collagen content of excised wounds 

 for prolonged periods. They found the rate of deposition to be relatively slow until 

 the 25th day when it started to rise rapidly reaching normal levels by the 50th 

 day. This was followed by a period of continued deposition until at the looth day 

 it surpassed normal skin in quantity per unit net weight and at 200 days, in 

 quantity per unit area. 



Tensile strength has long been recognized as a good index of wound healing 

 (Paget, 1853; Chlumsky, 1899). This can be readily determined by tensiometer 

 measurements of sutured skin wounds (Howes, Sooy, and Harvey, 1929) or by 

 employing an intraluminal balloon to measure the bursting strength of gastric 

 wounds (Harvey, 1929). The results of these investigations as well as many others 

 (Sandblom, 1944; Nelson and Dennis, 1951; Savlov and Dunphy, 1954a) have 

 shown that tensile strength does not rise till after a lag period of four to seven days. 

 This rise closely parallels the increase in collagen content, both of which reach 

 normal levels at the same time (Abercrombie and James, 1957). In view of our 

 present knowledge concerning the early chemical changes in a wound, Dunphy 

 and Udupa (1955) have reclassified wound healing into a "substrate" and a 

 "productive phase." The "substrate stage" persists for the first four to five days 

 during which time mucopolysaccharide and reticulin content are elevated and 

 the groundwork laid for the subsequent "productive stage" when collagen is 

 formed. This terminology is more realistic than the old classification in which 

 healing was divided into an initial lag phase and subsequent period of fibroplasia. 



Literature p. yoj 



