14 PRINCIPLES OP TETEBINAET SUEGEKY 



painful and somewhat s-wollen. In about one week per- 

 manent union takes place, with a little cicatrix at the site 

 of incision. 



Describe the microscopical changes in healing by first intention. 

 White blood cells emigrate from the neighboring vessels 

 and invade the edges and wound cement. This cellular 

 infiltration is due to the traumatic irritation of the parts, and 

 is not the result of the presence of bacteria, as is the case in 

 healing by second intention. In healing by first intention it 

 is an expression of reaction by the injured tissues, while in. 

 healing by second intention it represents a purulent infiam- 

 mation. The greatest number of leucocytes in the woundL 

 edges are met with on the third day ; after that they either 

 return to the blood vessels or die. 



Describe the process of cicatrization. 



The fibroblast produces the scar tissue. These are 

 roundish cells which arise through proliferation of the 

 endothelial cells of the vessels and those connective tissue 

 cells which are present. The fibroblasts increase in size, and 

 epithelioid, spindle and club shaped cells form ; these again 

 change into fibrillar connective tissue cells, which in turn 

 form the scar tissue proper. Vascularization of the wound 

 eJges takes place at the same time, the new vessels being 

 formed by a process of budding from the walls of the cut 

 capillaries. The young tissue formed by the fibroblasts plus 

 the newly created blood vessels is termed granulation tissue, 

 which shrinks as soon as the fibroblasts change into con- 

 nective tissue cells, the capillaries close, at which moment 

 scar tissue proper is formed. The last step in healing by 

 first intention consists in the skinning over of the scar tissue, 

 the cells springing from the epithelial cells upon the edges. 



