FAT METABOLISM IN THE LIVER 89 



or a free radical related to acetyl phosphate, is a main inter- 

 mediate in the synthesis and degradation of fats. It is, therefore, 

 of considerable interest in connection with fat metabolism as a 

 whole to consider the function which may be performed by long- 

 chain aldehydes. These substances have been unduly neglected 

 by the biochemists, possibly because they so readily undergo 

 polymerization and oxidation when treated by the common 

 methods for examination of fats. 



It was decided to study this problem in the liver of rats and 

 mice. A concurrent study was also made of aldehyde in rela- 

 tion to absorption of fat from the digestive tract. 



The material used in these experiments was fixed either in neu- 

 tral formaldehyde or in 8 percent formaldehyde -f- 5 percent 

 acetic acid. 



Absorption of Fat from the Digestive Tract 



Mice were fed with either emulsified olive oil or emulsified 

 oleic acid ; they were killed at intervals up to 7 hours after feed- 

 ing; and various sections of the small intestine were examined. 

 The fat droplets found in the intestinal epithelial cells were usu- 

 ally completely lacking in aldehyde, especially when a consider- 

 able amount of fat had been fed to the animals. When mice were 

 fed on a diet containing a significant but small amount of fat, the 

 occasional droplets of fat which are found in the cells often con- 

 tain a considerable amount of aldehyde, and there may be a con- 

 siderable amount of aldehyde distributed diffusely in the cyto- 

 plasm of the epithelial cells. But, when there is a considerable 

 flow of fat droplets through the cells, no aldehyde can be observed. 

 It thus seems clear that long-chain aldehydes are not concerned 

 with either the absorption of fat or fatty acid into the cells, or 

 with the transport of fat or fatty acids through these cells. 



Fat Metabolism in the Liver " 



The results obtained depended somewhat on the diet. When 

 the diet contained fat, protein, and carbohydrates, considerable 

 areas of the liver, as seen in tissue sections, contained a diffuse 

 distribution of aldehyde in the cytoplasm. There appeared to be 

 no free aldehyde in the nucleus. When the cells contained fat 

 droplets, each droplet appeared to be surrounded by a spherical 

 shell containing a high concentration of aldehyde. There were 



