CHAPTER VII 



LIPID DISTRIBUTION IN SPECIFIC TISSUES 

 AND IN THEIR SECRETIONS 



1. Introduction 



Although there are marked variations in the composition of the fat of the 

 entire animal as related to species, much greater differences exist between 

 the lipids present in the several tissues. Since some of the tissues which 

 play important roles in metabolism are relatively insignificant in the total 

 mass of the body, information concerning the lipids in these tissues is un- 

 obtainable on the basis of the lipid pattern of the animal as a whole. For 

 this reason, a detailed review of the composition of the separate tissues is of 

 importance. The carotenoid and fat-soluble vitamin components of these 

 tissues are discussed more fully in Volume III. 



2. Lipids Present in the Liver 



The liver plays an important and unique role in the metabolism of the 

 various lipid components. Although, under normal circumstances, the liver 

 lipids consist primarily of phospholipids and neutral fats, this organ may, 

 under certain conditions, contain larger accumulations of cholesterol (up to 

 9-6%) 1 ; in Niemann-Pick's disease, sphingomyelin comprises a larger than 

 usual proportion of the lipids. 2 ' 3 In Gaucher's disease, the amount of 

 cerebrosides in the liver is somewhat increased. In various types of fatty 

 livers, on the other hand, the proportion of triglyceride fat to the non- 

 glyceride moiety is greatly increased, due to the large accumulation of the 

 former fraction. These types of abnormalities in the storage of liver lipids 

 are discussed in Chapter VI. 



It is believed that newly absorbed fat is worked over in the liver to alter 



1 N. R. Blatherwick, E. M. Medlar, P. J. Bradshaw, A. L. Post, and S. D. Sawyer, 

 /. Biol. Chem., 103, 93-106 (1933). 



2 E. Klenk, Z. physiol. Chem., 235, 24-36 (1935). 



3 C. Tropp and B. Eckardt, Z. physiol. Chem., 243, 38-42 (1936). 



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