EPITHELIALIZATION CHEMICAL CHANGES 



685 



Phlorhizin poisoning, on the other hand, produces a drop in skin gkicose levels 

 with no change in glycogen content. 



Bradfield (1951) has postulated that the wound environment is more anaerobic 

 than that of normal skin. The migrating epithelium is greatly thickened; the 

 underlying vessels have been destroyed by the wounding process; and, in addition, 

 a heavy eschar overlies the entire area. Under these conditions, epithelial cells are 

 forced to rely on anaerobic metabolic pathways to furnish an equivalent amount 

 of energy in order to carry on their normal functions. A similar mechanism had 

 previously been suggested by Dempsey and Wislocki (1944) to explain the 

 presence of glycogen in the placenta. Scothorne et al. (Scothorne and Scothorne, 



Fig. 9. Photomicrograph showing the wound edge of a threeweek old human burn. The 



epithelium contains glycogen in all layers except the basal and lower stratum germinativum 



(Periodic Acid-Schiff stain, X 105). Gly — glycogen; Ep — epithelium; Der — dermis. 



1953) believed that skin glycogen is a degenerative phenomenon caused by 

 a reduced blood supply and resembling the accumulation in the rodent vagina at 

 pro-oestrus. 



When skin is cultured in iilro the edge of the explant resembles, in many ways, 

 a wound margin. The epithelial layers are increased in number, as at a wound 

 edge, and out- wandering cells of the explant have all the morphological characte- 

 ristics of migrating epithelium in wounds (Lewis et al., 1949), thus providing an 

 excellent opportunity to eliminate local environmental effects since the explant 

 and its out-wandering cells have precisely the same environment. Under these 

 circumstances, Washburn (1954b) found a glycogen pattern identical to that 

 of an in vivo wound : namely, that the epithelium of the explant itself contains no 

 glycogen while those cells at the border and in the out-wandering area do ac- 

 cumulate it. 



If a change in local environment fails to explain deposition of glycogen, what 



Literature p. 703 



