144 II. DIGESTION AND ABSORPTION OF FATS 



that the feeding of monoglycerides resulted in the formation of triglycer- 

 ides, a fact which was interpreted as indicative of complete hydrolysis of 

 the monoglyceride preliminary to absorption. 



Finally, the more recent studies with fatty acids and soaps have confirmed 

 the earlier investigations in demonstrating the absorbability of these sub- 

 stances. These studies included an investigation of the relationship be- 

 tween calcium salts and the absorption of fatty acids, 681-684 a comparison 

 of the absorption of fatty acids with that of their triglycerides, 685 as well as 

 a consideration of the role of the adrenal cortex in the absorption of fatty 

 acids. 686 - 687 For a further discussion of the absorption of fat in the form 

 of neutral fat, di- or monoglycerides, or as fatty acids or soaps, see page 151, 

 where the evidence for the several theories on fat absorption is discussed. 



b. Theories of Fat Absorption. The mechanism by which the ingested 

 fat passes into the wall of the intestine and from there into the lymph or 

 portal blood has been the object of much experimental work and of con- 

 siderable conjecture. The appearance of the fine emulsions in the intes- 

 tinal contents, as well as in the chyle from the thoracic duct, would seem 

 to offer some evidence that the process of absorption of fat involves the 

 passage of this substance in sufficiently fine droplets through the wall of 

 the gut. 



(a) Early Theories on Fat Absorption. Schafer 688 was one of the first to 

 advance proof that fat is absorbed in particulate form. He believed that 

 the leucocytes played an important role in the process, and aided in the 

 transfer of fat into the epithelial cells. It was recognized that, during ab- 

 sorption, there is no rigid cell membrane on the open (lumen) side of the 

 columnar epithelium. The surface could readily be indented, and it was 

 believed that leucocytes might work their way into the cells as well as be- 

 tween them. Fat globules of various sizes were observed within the epi- 

 thelial cells during absorption. Usually the largest globules are between 

 the nucleus and the outer border of the cell (toward the lumen), while those 

 near the basement membrane are small, as a rule. In some instances the 

 majority of the fat was found in the outer portion of the cell, while, in other 



681 M. H. Givens, J. Biol. Chem., SI, 441-444 (1917). 



682 A . W. Bosworth, H. H. Bowditch, and L. A. Giblin, Am. J. Diseases Children, 15, 

 397-407 (1918). 



683 O. F. Boyd, C. L. Crum, and J. F. Lyman, J. Biol. Chem., 95, 29-41 (1932). 



884 A. L. S. Cheng, M. G. Morehouse, and H. J. Deuel, Jr., /. Nutrition, 87, 237-250 

 (1949). 

 686 R. Hoagland and G. G. Snider, J. Nutrition, 26, 219-225 (1943). 

 fiM I,. A. Bavetta and H. J. Deuel, Jr., Am. J. Physiol, 136, 712-715 (1942). 

 fi87 L. A. Bavetta, Am. J. Physiol., 11,0, 44-46 (1943). 

 688 E. A. Schafer, Intern. Monatsschr. Anal. Hisiol., 2, 6-29 (1885). 



