ABSORPTION AND TRANSPORT OF FATS 



171 



Table 20 



Comparative Distribution in the Body of Absorbed Fatty Substances as 



Postulated by the Lipolytic and Partition Theories 



Lipolytic theory 



Partition theory 



1. Fatty acid fraction 



2. Glyceride fraction 



After resynthesis, triglycer- 

 ides pass through the lac- 

 teals and the thoracic duct 

 into the systemic circula- 

 tion 



Negligible amounts pass up 

 the portal vein to the liver 



Not absorbed as such. Re- 

 synthesized from fatty 

 acid and glycerol and trans- 

 ported as described above 



Mainly passes by the portal 

 vein to the liver* ~ d 



Passes to the systemic blood 

 via the lacteals and tho- 

 racic duct, and so to the fat 



depots'* 



« A. C. Frazer, Physiol. Revs., 26, 103-119 (1946). 

 b A. C. Frazer, Analyst, 63, 308-313 (1928). 

 c A. C. Frazer, /. Physiol, 102, 329-333 (1943). 

 d A. C. Frazer, ./. Physiol, 102, 306-312 (1943). 



triglycerides or fatty acids. Under either condition, the fat would reach 

 the intestinal cells in the form of fatty acids, which would then be syn- 

 thesized into the triglycerides; these would be transported to the tissues 

 and to the liver via the lymphatic system, a small fraction probably passing 

 to the liver by way of the portal circulation. 



However, Frazer 808 showed that the pathway of absorption in the rat 

 varied markedly when neutral fat was fed, as compared with the situation 

 which obtained when fatty acids and glycerol were given. When olive 

 oil was administered, the intestinal cells were filled with fat particles, the 

 lacteals had a distinctive milky appearance, a characteristic postabsorp- 

 tive lipemia obtained, and Sudan-colored oil could be traced to the fat de- 

 pots. No appreciable change in the portal blood fat could be noted, and 

 only a slight deposition of Sudanized fat could be observed in the liver. 



On the other hand, when fatty acids and glycerol were fed, the picture 

 was completely reversed. The intestinal cells had a granular appearance, 

 the milkiness in the lacteals was absent, no postabsorptive lipemia was 

 noted, and no deposition of dye was found in the tissues when Sudan IV 

 was added to the fatty acids in the intestine. Moreover, an increase in the 

 fatty material was noted in portal blood, and an extensive deposition of 

 Sudan-containing fat was observed in the liver. When an excess of lipase 

 was administered to an animal receiving the triglyceride, the picture was 



808 A. C. Frazer, J. Physiol, 102, 306-312 (1943). 



