48 Principles Of veterinary sUrGErY 



various histological structures such as nerve-fibres, muscle- 

 fibres, and cells, and cause dropsical vacuoles. Mucoid de- 

 generation is frequent especially in catarrhal inflammations; 

 hyalin and amyloid, common in chronic. When the acute 

 degenerative changes of inflammation subside, leaving an 

 ulcer or abscess, the development of formative cells from 

 pre-existing cells occurs for regenerative purposes. If a lim- 

 ited amount of tissue has been destroyed, the ordinary pro- 

 cesses of repair occur, each new tissue arising from old cells 

 of the same kind. On the other hand, if there has been an 

 extensive loss of substance, granulations form, which are ulti- 

 mately converted into cicatricial tissue or scar-formation. 



Microscopical Picture of an Acute and Chronic Infiam- 

 mation. — ^Histologically, the acute inflammation is character- 

 ized by a cloudy swelling and parenchymatous degeneration 

 of the epithelial cells, which are enlarged, granular, and vacu- 

 olated, and also poorly stained, especially the nuclei. Marked 

 infiltration of leucocytes occurs in the tissues irritated, a 

 round cell-infiltration. Any of the exudates described above 

 may be seen in the inflamed areas and can be differentiated 

 by special stains. If the irritant be microparasites, they can 

 many times be demonstrated in the tissues. 



A chronic inflammation is characterized by the formation 

 of connective tissue, which as regards its cells, can be seen 

 in all stages of development — small I'ound cells, epithelioidal 

 cells, fibroblasts, matured connective-tissue cells, giant and 

 plasma cells. The younger the tissue, the more cellular it 

 is, while in old chronic tissues, fibres predominate, together 

 with marked forms of degeneration. Exudates may or may 

 not be present. The irritant can more often be demon- 

 strated than in the acute inflammation. 



As will be seen from the foregoing, there is nothing in 

 the histological findings of an ordinary inflammation that 

 would indicate the exact cause of the irritation unless the ir- 



