ULTRASTRUCTURAL CHANGES IN THE SKIN OF THE ORAL MUCOSA AFTER GUNSHOT AND NONGUNSHOT INJURIES OF THE JAWS IN RATS IN THE EXPERIMENT

Abstract

In order to study the ultrastructural changes in the skin, oral mucosa and bone tissue, the following tasks were set: – to study the ultrastructure of changes in the skin and mucous membrane of the oral cavity after gunshot wounds of the jaws in the experiment on rats; – to study the ultrastructure of changes in the skin and mucous membrane of the oral cavity after non-gunshot damage to the jaws in an experiment on rats. Material and methods of the study: The work was performed on 7 adult Wistar rats, which were divided into 3 groups: Group I – control, intact animal; Group II – group of modeling mechanical damage in the rat; Group III – modeling of gunshot damage. For electron microscopic examination, fragments of bone and soft tissue of the rat jaw were fixed in a 2.5% solution of glutaraldehyde in phosphate buffer at a pH of 7.4, followed by additional fixation with 1% solution of osmic acid at the same pH of the buffer solution. The samples were then dehydrated in alcohols of increasing concentration. The material was impregnated and encapsulated in a mixture of Epon-Araldite epoxies. Subsequently, ultrathin sections were contrasted using the Reynolds method. The results of the study showed that after a gunshot wound, the studied tissues showed more significant manifestations of productive inflammation than after a mechanical fracture. Gunshot wound involves wider areas of destructive and necrotic changes in the soft tissues of the rat than mechanical fracture. They consisted in the accumulation of a large number of cells of histiogenic origin with a predominance of macrophages and mast cells. Moreover, some of the mast cell granules showed signs of histamine release, which is characterized as a reaction to an allergic component, possibly in our case to gunpowder. In addition, after the gunshot wound, the tissues suffered significant and extensive damage: destruction and necrosis of both connective tissue cells and collagen fibers. At the same time, in this area, a greater number of fibroblasts with activation of protein synthesizing processes aimed at collagen synthesis and formation of collagen fibrils was observed than after a mechanical fracture. On the 7th day after gunshot wound, productive inflammation in the proliferation phase with elements of reparative regeneration was observed in the soft tissues of the rat. On the 7th day after mechanical fracture in the soft tissues of the rat, the intensity of productive inflammation is significantly lower than after gunshot wound.