IV EPITHELIALIZATION 683 



dicular to the direction of normal tension. The role of tension is also exemplified in 

 extensive burns, the scars on non-mobile surfaces blanch and flatten much earlier 

 than those situated in areas of motion. Hypertrophy continues until motion is 

 overcome, and in many instances marked flexion and extension deformities are the 

 result. Skoog (1948) studied this process in Dupytren's contracture and concluded 

 that active motion resulted in trauma and formation of microscopic hemorrhages 

 in the fibrous tissue followed by further fibrosis and thickening of the scar. 



Fig. 8. Seven-year old girl one year following skin grafting of a third-degree burn. There 

 is a severe contracture and scar hypertrophy involving the areas of "push-pull" tension. 



v. CHEMICAL CHANGES ASSOCIATED W^ITH EPITHELIALIZATION 



Normal skin has been extensively investigated by both biochemical and histo- 

 chemical techniques. These studies have proved complementary in many respects, 

 the former serving as a quantitative, and the latter as a qualitative means of 

 evaluating various substances. During wound healing, there is a variation from the 

 normal chemical pattern, particularly with respect to glycogen, ribosenucleic acid, 

 deoxyribosenucleic acid, acid and alkaline phosphatases, succinic dehydrogenase, 

 and non-specific esterase. 



The presence o{ glycogen in mammalian skin has been known since the description 

 of Claude Bernard (1859). The quantity varies considerably, fetal skin is relatively 

 rich in this carbohydrate (Lombardo, 1907, 1934; Susakawa, 192 1), in adult 

 human epithelium it is limited to small amounts above the rete pegs in the stratum 

 spinosum and about the orifices of pilosebaceous units (Unna and Golodetz, 1909; 

 Unna, 1926; Mancini, 1948; Bolliger and McDonald, 1949; Montagna et al., 

 1 951; Montagna and Lobitz, 1952). 



Literature p. yoj 



