FATTY INFILTRATION. 



277 



Fatty infiltration may be a physiological or a pathological 

 process. It occurs physiologically under the skin, between 

 muscles and surrounding organs ; pathologically in abnormal 

 places, as between individual muscle- fib res, and in normal 

 situations in great excess, as in general obesity. It is due 

 to either the over-production of fat or its deficient consump- 

 tion. Fatty infiltration of the liver may be produced experi- 

 mentally in the lower animals by an excess of fatty food and 

 restriction of oxidation by preventing muscular movement. 

 In phthisis, cancer, and severe anaemias the explanation seems 

 to be found in lessened oxidation. In chronic alcoholism the 

 change often occurs, the alcohol being oxidized in place of the 

 fat. 



The fat-drops are larger than in fatty degeneration, and are 

 found either between the tissue-elements or within the cells, 



FIG. 112. 



Fatty infiltration of muscle from a case of stiffening of the ankle by an epithelioma 

 of the skin over it. The muscular fibres are narrowed, and adipose tissue ap- 

 pears between them. X 80 (Coats). 



the nucleus and protoplasm being pushed one side until the 

 cell is like a vesicle filled with fat (Fig. 112). The liver 

 is frequently affected in advanced phthisis. On section oil 

 accumulates on the knife or may be scraped from the cut 

 surface. The affected organ is enlarged, heavy but of less 

 specific gravity, soft, less elastic and doughy, and of a light 

 yellow color, or mottled, if the change is not uniform through- 

 out. In the liver the change is particularly noted in the 

 periphery of the acini, giving them a pale yellow margin. 



