PHYSIOLOGY OF ADIPOSE TISSUE 609 



nervous stimuli and, in fact, that nerves are not present in these tissues, 

 later investigators have reached opposite conclusions. 412-414 Nordmann 415 

 believed that the nerve supply to adipose tissue was dependent upon that to 

 the blood vessels supplying this tissue. However, considerable proof that a 

 nerve supply exists not only to the blood-vessels but also to the cells has 

 been furnished by Hausberger 414 and by Boecke. 416 Goering 412 suggests 

 the existence of a nerve center in the floor of the third ventricle which reg- 

 ulates the deposition and the disappearance of fat. 



The blood-vessels in adipose tissue are likewise characteristic. Gersh 

 and Still, 417 who made a quantitative examination of the capillary supply 

 of adipose tissue, found that, in rats, the capillaries in the fat depots showed 

 no orientation such as occurs in muscle tissue, but formed loose meshes 

 running in all directions in the tissues enclosing the fat cells. Considerable 

 variation was noted in the number of capillaries in different parts of the 

 tissue, but all fat cells were in contact with at least one vessel. 



When a comparison of the circulation in the adipose tissue and muscle, 

 respectively, is based upon the relation of the surface of the capillary bed to 

 the volume of tissue supplied, the ratio is 52 in fat-rich tissue and about 222 

 in fat-poor tissue. This latter figure corresponds to the value in poorly 

 supplied muscle. On the other hand, when the comparison is made be- 

 tween the surface area of the capillaries and the volume of the proto- 

 plasm — which is a better standard of comparison for metabolic purposes — 

 the ratio for fat-rich tissue based upon surface of open capillaries is 978, 

 while that based upon total capillaries is 2160. This means that, for met- 

 abolic purposes, the capillary bed of adipose tissue is richer than that of 

 muscle. 



(8) Changes in Fat Composition Occurring in Fat Depots 



The fat deposited in adipose tissue is characteristic of the animal as well 

 as of the site of deposition. The composition of the depot fat can also be 

 influenced by diet, 372 as has been demonstrated by the feeding of trielai- 

 din, 46 or by the administration of deuterium-labeled fat. 418 Moreover, the 

 proportion of unsaturated acids present in this adipose tissue can be greatly 

 increased, particularly when the diet is low in protein and carbohydrate, and 



412 D. Goering, Z. ges. Anat., Abt. II, Z. Konslitutionslehre, 8, 312-335, 458 (1922). 



413 E. Wertheimer, Arch. ges. Physiol. (Pftiiger's), 213, 262-279, 287-297 (1926). 



414 F. X. Hausberger, Z. mikroskop.-anat. Forsch., 36, 231-266 (1934). 

 416 M. Nordmann, Z. ges. exptl. Med., 48, 84-110 (1925). 



416 J. Boecke, Z. mikroskop.-anat. Forsch., 33, 233-275 (1933). 



417 I. Gersh and M. A. Still, J. Exptl. Med., 81, 219-232 (1945). 



418 De W. Stetten, Jr. and R. Schoenheimer, J. Biol. Chem., 133, 329-345 (1940). 



