742 VII. LIPID DISTRIBUTION IN SPECIFIC TISSUES 



The composition of the whole brain, as well as of the gray and white 

 matter, is given in Table 8 and that of the nerves in Table 9. 



Table 8 

 The Composition of Whole Adult Brain, of the Gray Matter of the Cortex, 



AND OF THE WHITE MATTER OF THE CORPUS CaLLOSUM" 



Fresh 



adult Gray White 



Substance brain, % matter, % matter, % 



Water 77 84 70 



Solids 23 16 30 



Proteins 8-9 7 . 5 s 8.7 



Total lipids 12-15 2 5 h 19.5 



Cholesterol 3.6-4.8 1.2* 3.1 



Phospholipids 5.7-6.9 0.8 6 9.0 



Cerebrosides 1.3-2.6 0.4 6 5.1 



Sulfolipids 0.66-1.8 2.3 



Extractives (Total) 2.1-2.9 3.0 ft (1.0) 



Organic 1.1-2.0 — — 



Inorganic . 9-1 .0 — — 



Ash 1.5 1.0 1.75 



" Adapted from I. H. Page, Chemistry of the Brain, C. C Thomas, Springfield, 111., 

 1937. 



b Figures cited by E. S. West and W. R. Todd, Textbook of Biochemistry, Macmillan, 

 New York, 1951, p. 422. 



The composition of the brain shows marked variation in various portions 

 of its structure. For example, the white matter has about twice the con- 

 tent of total solids that is found in the gray matter. The high solid content 

 of the white matter is accounted for largely by the increased proportion of 

 lipid as compared with gray matter. The chief lipids in the brain and 

 nervous tissues are cholesterol, phospholipids, cerebrosides, and ill-de- 

 fined compounds known as sulfolipids or sulfatides. Practically no neutral 

 fat is present in the brain and nerves of the adult. 



a. Phospholipid Components in the Brain. In the early studies of 

 Thudichum, 221 the cephalin and lecithin content of the moist gray matter 

 was given as 0.33 and 1.59%, and that of the moist white substance as 

 0.09 and 0.73%, respectively. Bloor 23 recorded the following figures for 

 whole beef brain: cephalin, 2.36%; lecithin, 2.23%; and acetone-soluble 

 products, mostly cholesterol, 1.88%. 



The lecithins and cephalins in brain consist of both the a- and the /3- 



221 J. W. L. Thudichum, Die chemische Konstitution des Gehirns des Menschen und der 

 Tiere, Pietzcker, Tubingen, 1901 ; cited by W. R. Bloor, Biochemistry of the Fatty Acids, 

 Reinhold, New York, 1943, p. 203. 



