THE ABSORPTION OF THE FOOD-STUFFS 



835 



rapidly enlarge till they occupy the greater part of the cell lying 

 between the nucleus and the basilar striated border. Most observers 

 are agreed that no fat globules are to be seen within the border itself. 



According to Altmann the fat granules found in the cells during absorption 

 are themselves produced by a transformation of fuchsinophile granules which 

 are present in the cell even during the fasting condition. At an early stage 

 the small fat granules can be stained so as to show a distinct fuchsinophile 

 envelope. Altmann interprets this appearance as showing that the epithelial 

 cells take up the fat in a dissolved form, probably in a hydrolysed condition, 



A 



B 



FIG. 349. A. Vertical section through intestinal epithelium of a rat during 

 fat absorption. B. Horizontal section through deeper parts of the cells, 

 showing excretion of fine fat globules into the intercellular clefts. 

 (RETTTEE.) 



and that a process of synthesis then occurs in the granules leading to the 

 formation and accumulation of fat. When the process of absorption is 

 proceeding actively the meshes of the villus contain a number of free fat 

 granules, and the leucocytes in these meshes are generally found also full of these 

 granules. According to Zawarykin and Schafer an important function in the 

 transfer of the granules from epithelial cells to central lacteal was performed 

 by the leucocytes. These were supposed to take up the fat granules extruded 

 by the epithelial cells at the base of the villi, to wander into the central lacteal 

 where they broke down, furnishing in this way the molecular basis of the 

 chyle as well as its protein constituents. This view was strongly combated by 

 Heidenhain, who pointed out that many of the granules staining darkly with 

 osmic acid were not necessarily fat, and that the number of leucocytes within 

 the villi were hardly sufficient to account for the amount of material observed. 

 According to Reuter the epithelial cells take up fat in a dissolved condition 

 through the striated border, and deposit it as granules of neutral fat in the 

 inner portion of the protoplasm. From here the fat is passed on by the proto- 

 plasm by the side of the nucleus and extruded in the form of very fine granules 

 in the deeper parts of the inter-epithelial clefts, which thus function as true 

 excretory channels for the epithelial cells (Fig. 349). 



