LIPID DISTRIBUTION IN THE CELL 603 



The total fat in the depots may be reduced by 95% as a result of prolonged 

 starvation, compared to a loss of 70% in the spleen, to one of 50% in the 

 liver, and to one of only 5% in the brain, spinal cord, eyes, and heart. 374 

 On the other hand, the tissues may contain an extremely high level of fat. 

 Smith 375 cited a case of hypothalamic injury in which the fat made up 74% 

 of the total carcass weight. Hetherington and Ranson 376 reported that the 

 depots in the subcutaneous tissue, in the omentum, and in the mesenteries 

 of the viscera were filled with fat, as were also those in the perirenal tissues, 

 the pericardium and, in fact, in every location where adipose tissue nor- 

 mally exists. Moreover, large amounts of fat were stored in the liver. 

 This organ was yellow, and was twice its normal size. The presence of 

 twice the normal content of fat in these livers is quite common. This 

 would account for about four times the normal amount of fat. However, 

 instances have been reported in which, when choline-low diets were given, 

 the enlarged livers contained as much as twenty times the amount of lipid 

 normally present (see page 635) . 



Extreme obesity can be produced experimentally by injury to the hy- 

 pothalamus. 376 A number of investigators 37G_379 have described an experi- 

 mental obesity which may begin to develop within a few hours after an 

 operation in which the hypothalamus is injured. An adult female rat may 

 increase in weight by 15% within the first twenty-four hours after opera- 

 tion, 380 and the rate of gain will continue at ten times the normal for several 

 weeks. The gain is not maintained indefinitely, as the body weights of the 

 animals eventually reach a plateau. Brobeck 380 reviewed the subject of 

 obesity in animals with hypothalamic lesions. For a further discussion of 

 the deposition of excessive amounts of fat, see page 623. 



6. The Lipid Distribution in the Cell 



Lipids are present in the cell membrane, where they serve structural 

 rather than metabolic purposes. Investigations of a number of the cell 

 components have been rendered possible by the development of new 

 methods for the separation of various anatomical structures within the cell. 



374 M. R. Everett, Medical Biochemistry, 2nd ed., Hoeber, New York, 1946, p. 249. 



375 P. E. Smith, J. Am. Med. Assoc, 88, 158-161 (1927). 



376 A. W. Hetherington and S. W. Ranson, Anal. Record, 78, 149-172 (1940). 



377 A. D. Keller and W. Noble, Am. J. Physiol, 118, 79-80 (1935); 116, 90-91 (1936). 



378 P. E. Smith, Am. J. Anat., 45, 205-256 (1930). 



379 J. R. Brobeck, J. Tepperman, and C. N. H. Long, Yale J. Biol. Med., 15, 831-853 

 (1943). 



380 J. R. Brobeck, Physiol. Revs., 26, 541-559 (1946). 



