PHYSIOLOGIC FUNCTIONS 817 



there is marked decrease in the ratio of highly unsaturated fatty acids to 

 the fat-free dry weight of the subcutaneous tissues. This effect is inter- 

 preted as an indication that the EFA are used up in the formation of new 

 tumor tissue; the subcutaneous fat depots are undoubtedly called upon 

 to furnish the extra EFA ret^uired. Thus, growth may well be associated 

 with the metabolism of the essential fatty acids. 



Aaes-J0rgensen and Dam^^^"'^^ studied the effect on growth of several 

 levels of fat in the diet, as related to the essential fatty acid content of the 

 fats. It was found that male rats mahitained on diets containing 7% of 

 fat grew much better on lard (presumably containing essential fatty acids) 

 than on hydrogenated peanut oil,^^- whereas rats on a fat-free ration grew 

 at the same rate as did the rats on the hydrogenated peanut oil diet. An 

 increase of the amount of lard to 28% of the diet had little effect upon the 

 average growth rate, whereas an increase of the level of hydrogenated pea- 

 nut oil to 28% decreased the growth rate considerably.^*^ When the lard 

 or peanut oil was supplemented with linoleic acid, raw skim milk, or both, 

 an increase in the fat level from 7% to 28% increased the growth rate of 

 female rats. When supplemented hydrogenated peanut oil was given, the 

 increase in fat level had considerably less effect upon the weight gain.'*^'^^ 

 Rats given hydrogenated whale oil at a 7% level, and those on a fat-free 

 regimen, had the lowest growth rate.'^^ 



Panos and Finerty^^^ reported that female rats kept on a fat-free diet for 

 thirty-four weeks from the time of weaning attained a weight which was 

 80% of that of the controls. On the basis of organ weight per 100 g. of 

 body weight, the thyroid and adrenal glands were significantly smaller, 

 while the kidneys, liver and heart were larger, in the fat-free group than in 

 the controls. When fat was added to the diet of the deficient animals, a 

 rapid increase in body weight to control values occurred, associated with a 

 progressive relative decrease in the size of the kidneys, liver, and heart. 



These workers ^^^ also demonstrated that the estrus cycle was distinctly 

 irregular in female rats subjected to a fat-free diet. Ovarian weight was 

 not affected, but large numbers of deficient nuclei were present in the 

 interstitial tissues. The follicles and corpora lutea, however, appeared 

 to be normal. Since a significant decrease in the percentage of acidophils, 

 and an increase in basophils, occurred in the pituitary cells, it is suggested 



182 E. Aaes-J0rgeiisen and H. Dam, Brit. J. Nutrition, 8. 281-285 (1954). 

 18' E. Aaes-J0rgensen and H. Dam, Brit. J. Nutrition, 8, 285-289 (1954). 

 18* E. Aaes-J0rgensen and H. Dam, Brit. J. Nutrition, 8, 290-296 (1954). 

 i8« E. Aaes-J0rgensen and H. Dam, Brit. J. Nutrition, 8, 296-301 (1954). 

 '88 E. Aaes-J0rgensen and H. Dam, Brit. J. Nutrition, 8, 302-306 (1954). 

 '87 T. C. Panos and J. C. Finerty, /. Nutrition. 49, 397-424 (1953). 



