Ill 



WOUND CLOSURE 



673 



are close to the table edge of the chamber then the latent period is short. Chambers 

 located near a central artery or at the base of the ear in the neighborhood of large 

 vessels also exhibit shorter latent periods. Furthermore, if tissue within the 

 chamber is damaged, regrowth occurs within 24 hours from vessels already present. 

 It is generally accepted that the majority of ingrowth to a wound area occurs 

 from the lateral edges, but clinical and histological evidence does not support such 

 a view. An open wound, regardless of its size or depth, granulates uniformly from 

 the base and not from the periphery, as may be demonstrated in extensive human 

 burns, leg ulcers, etc. An excised area with soft tissue forming the base will 

 ultimately granulate regardless of the depth of excision, and fat, fascia, and muscle 

 are equally capable of forming granulation tissue. Exposed cortical bone, on the 



< ■4k *!"'-' -" ""♦ «»r*t 



Fig. 4. Photomicrograph of a ten-day old rat burn showing the dense column of fibroblasts 



which extends down through the wound area into the underlying subcutaneous tissue (Van 



Gieson stain, X 48). Ep — epithelium; Fib — fibroblasts 



other hand, fails to react in a similar manner and will sequestrate unless covered by 

 soft tissue. 



Histological sections of a wound invariably reveal a dense column of fibroblasts 

 arising from the deeper layers with a sharp laterally demarkation between this 

 column and the adjacent normal tissue. The base always extends to the area 

 beneath the dermis, suggesting that fibroblasts originate from the lower rather 

 than the peripheral aspects of the defect. Hartwell (1928, 1929, 1949, 1950, 1955) 

 has long maintained that subcutaneous fat and fascia play a dominant role in this 

 process. Gillman et al. (1956) verified his work and stated that there is also a down- 

 ward growth from the adjacent subepithelial connective tissue. The reticulin 

 pattern of the healing wound closely resembles that of the fibroblasts suggesting 

 the fibers are derived in part at least from those cells. 



Literature p. yoj 



