208 



HISTOLOGY. 



| Goblet-cells. 



sidered due to protoplasmic processes lodged in pores. Terminalb ars are 

 also present. The goblet cells have a thin top plate, which in sections is 



often ruptured to allow the 

 escape of mucus. This is 

 probably not artificial. Be- 

 tween the epithelial cells 

 there are narrow spaces into 

 which lymphocytes often mi- 

 grate (Fig. 234), and from 

 which some of them may 

 escape into the lumen of the 

 intestine. The lateral walls 

 of the epithelial cells are de- 

 scribed as modified ectoplasm 

 rather than true membranes. 

 Their basal ends rest upon 

 the tunica propria, which is 

 a reticular tissue containing 

 many small round cells in its 

 meshes and supporting a cen- 

 tral lymphatic vessel together 

 with numerous blood capil- 

 laries (Fig. 235). Smooth 



muscle fibers extend into it from the muscularis mucosae, and by 

 contraction they shorten the villus and empty its lymphatic vessel. 

 Eosinophilic cells, plasma cells and phagocytes may also be found in the 

 tunica propria of the villi. 



Interest in the villi centers 

 chiefly in their relation to the 

 absorption of nutritive ma- 

 terial from the intestinal con- 

 tents (chyme}. Fat, probably 

 in combination, is said to be re- 

 ceived by osmosis through the 

 cuticula. It appears in vacu- 

 oles in the outer part of the 

 cells, as shown in osmic acid 

 preparations, but neither 

 within nor in contact with the cuticula. It extends to the deeper part of the 

 cells and is found in the intercellular spaces between the epithelial cells. 

 It has been said that lymphocytes ingest it there and convey it to the cen- 



Cells of Paneth. 



FIG. 233. THREE INTESTINAL GLANDS FROM SECTIONS OP 

 THE ILEUM, THE ONE ON THE RIGHT FROM A MOUSE, 

 THE OTHER Two FROM A MAN. X 390. 



The left gland was from a preparation fixed in Zenker's 

 fluid, the other two were fixed in a potassium bichro- 

 mate and formaline mixture. 



Epithelium. 



Tunica 



propria. 



FIG. 234. FROM A SECTION OF THE SMALL INTESTINE 



FROM A KITTEN SEVEN DAYS OLD. X 250. 

 The epithelium on the left contains many wandering 



leucocytes (lymphocytes). The epithelium on the 



right contains but three. 



