708 VII. LIPID DISTRIBUTION IN SPECIFIC TISSUES 



the nature of its fatty acid pattern so that it will conform to the type usu- 

 ally stored by that particular species; the reworked fat is then transferred 

 to the fat depots for storage. Hepatic cells, also, have the ability to syn- 

 thesize the fatty acids, 4 as well as cholesterol. 5-7 The liver is the chief 

 organ in which the fatty acids are oxidized, with the resultant production 

 of ketone bodies. Thus, the liver is the only organ in which a production 

 of ketone bodies can be demonstrated by the higher content of acetone 

 bodies in the venous blood coming from the organ, as contrasted with that 

 in the arterial blood supplying this organ. 8 - 9 Fats are likewise desaturated 

 in the liver, as shown by the fact that the iodine values of the neutral fat 

 and phospholipid fractions are invariably higher than the corresponding 

 fractions in other tissues. 10 



Although phospholipid synthesis takes place in a number of organs, the 

 liver is one of the most important sites for its synthesis. 11 It is now recog- 

 nized that a number of tissues may bring about esterification of free choles- 

 terol; however, the master tissue which appears to mediate the change is 

 the liver. 12 Another more striking transformation of cholesterol, brought 

 about by hepatic tissue, is its conversion to bile acids. 13 Carotene occurs 

 in maximum concentration in the liver of man and of animals which are ca- 

 pable of absorbing it without changing it to vitamin A 14 - 15 ; furthermore, this 

 organ is the site of transformation of the pigment to vitamin A in these 

 species. The liver is almost universally regarded as the chief storehouse 

 for vitamin A. This is true not only for fishes, 16 in which vitamin A plays 

 an especially important role, but also for a large variety of reptiles, birds, 

 and mammals, including man. 17 The liver also serves as a site for the stor- 

 age of vitamin D. 18 In addition to all of the functions which concern the 



4 K. Bloch and W. Kramer, /. Biol. Chem., 173, 811-812 (1948). 



5 H. N. Little and K. Bloch, J. Biol. Chem., 183, 33-46 (1950). 

 6 1. Zabin and K. Bloch, /. Biol. Chem., 185, 131-138 (1950). 



7 P. A. Srere, I. L. Chaikoff, S. S. Treitman, and L. S. Burstein, /. Biol. Chem., 182, 

 629-634 (1950). 



8 1. L. Chaikoff and S. Soskin, Am. J. Physiol, 87, 58-72 (1928-1929). 



9 H. E. Himwich, W. Goldfarb, and A. Weller, ./. Biol. Chem., 93, 337-342 (1931). 



10 W. R. Bloor, Ann. Rev. Biochem., 1, 267-298 (1932). 



11 I. Perlman, S. Ruben, and I. L. Chaikoff, J. Biol. Chem., 122, 169-182 (1937). 



12 M. L. Nieft and H. J. Deuel, Jr., J. Biol. Chem., 177, 143-150 (1949). 



13 K. Bloch, B. N. Berg, and D. Rittenberg, J. Biol. Chem., 149, 511-517 (1942). 



14 H. Willstaedt and T. Lindqvist, Z. physiol. Chem., 240, 10-18 (1936). 



15 C. L. Connor, Am. J. Pathol, 4, 293-308 (1928). 



16 H. R. Rosenberg, Chemistry and Physiology of the Vitamins, Interscience, New York- 

 London, 1945. 



17 H. B. Jensen and T. K. With, Biochem. J., 33, 1771-1786 (1939). 



18 W. Heymann, /. Biol. Chem., 118, 371-376 (1937). 



