LIPID STORAGE UNDER ABNORMAL CONDITIONS 635 



b. Description of Fatty Livers. The pathologic fatty livers which de- 

 velop as a result of the absence of choline in the diet have a characteristic 

 appearance. They are greatly enlarged, due to their engorgement with fat. 

 Whereas the liver usually accounts for approximately 3 to 4% of the total 

 body weight, the average proportion of the body weight made up by the 

 liver, in fifteen female rats receiving a choline-free diet with 2% cholesterol, 

 was 6.68%, in the experiments of Deuel et al. m The actual amounts of 

 water, protein, and ash remain constant in the fatty livers, although the 

 percentage of these components decreases inversely with the increase in 

 liver lipids. Liver lipids normally comprise 3 to 4% of the total moist 

 weight of the liver, while the mean proportion of liver lipid in the group of 

 female rats receiving 2% cholesterol was 37.9% of the moist liver weight, 

 and the average water content was only 47.3%. Individual livers were 

 found to have as much as 45% of lipids. The increased lipid in the fatty 

 livers was composed almost exclusively of neutral fat. This fraction did 

 not increase in the other tissues of animals with fatty livers, except for a 

 slight increase in the brain, when cholesterol fatty livers, or hepatic fat de- 

 posits following liver feeding, were tested. Other lipid components re- 

 mained constant in the fatty livers, except for choline, which was 

 decreased. 561 Fatty livers are white, contain little blood, and are exceed- 

 ingly brittle. They are so fragile that it is almost impossible to remove 

 them whole. 



Extremely fatty livers containing 68% of fat (dry-weight basis) have 

 been obtained 562 in choline-deficient rats fed a 20% protein diet for one 

 week, following seven days of fasting or twenty-one days of protein deple- 

 tion. Under similar conditions, normal liver fat was maintained in rats 

 receiving adequate dietary choline. 



One of the most striking features of pathologic fatty livers produced by a 

 choline-low diet is the rapidity with which they develop. When rats pre- 

 viously on a stock diet were fed the diet described by Best and Channon. 563 

 Deuel and Hallman 564 observed a marked increase in liver lipids within 

 twenty-four hours; this was followed by a progressive rise in these com- 

 ponents which did not reach the maximum value until more than sixteen 

 days later. The data illustrating the rate of development of fatty livers 

 are indicated in Table 21 (page 636). 



The response of the female rats to the choline-free diet is much more pro- 



561 T. Tokushima, M. Yoshihara, and T. Shimojo, /. Biochem. (Japan), 39, 5 (1952). 



562 O. M. Hale and A. E. Schaefer, J. Nutrition, 46, 479-487 (1952). 



563 C. H. Best and H. J. Channon, Biochem. J., 29, 2651-2658 (1935). 



564 H. J. Deuel, Jr., and L. F. Hallman, J. Biol. Chem., 140, 545-554 (1941). 



