186 MICROSCOPIC ANATOMY OF THE ORGAXS. 



cells we find both on the villi and in the glands mucus-pro- 

 ducing cells, the so-called goblet cells (see under Epithelium). 

 The cells full of secretion possess no true cell membrane, but 

 only a thickened ectoplasm, which undergoes no mucoid change 

 and corresponds with the crusta of F. Schulze (Fig. 131). 

 These goblet cells are unevenly distributed, but are especially 

 abundant in the large intestine. 



It is not fully understood whether the goblet cells are a 

 different kind of cell or a modified form of the cylindrical 

 cells. Some authors claim that every young cylindrical cell 

 has the power of changing into a goblet cell, and that a cylin- 

 drical cell is really a resting goblet cell. Most writers, how- 

 ever, believe that the two kinds of cells are separate and 

 distinct, and that there is only a superficial resemblance 

 between the resting goblet cell and the cylindrical cell. Many 

 hold that mucus can be produced by any of these cells. In 

 fasting, the number of goblet cells increases ; likewise during 

 active digestion, as also in poisoning with pilocarpine, they 

 become more numerous. In connection with the regeneration 

 of these cells, Bizzozero has observed that many karyokinetic 

 figures are found in the glands, and almost none on the villi. 

 Thus Lieberkiihn's glands seem to be a place of regeneration 

 for epithelium which has been destroyed by oversecretion. 

 Bizzozero claims that these new cells are pushed up to the villi 

 from the glands, and the differences in form of the cells is 

 due to their age. On this theory may be explained the great 

 abundance of goblet cells in the large intestine. Those on the 

 villi are destroyed quickly, and must be replaced by cells 

 formed in the glands. This condition is not present in the 

 large intestine, owing to the lack of villi there, and the goblet 

 cells accumulate. 



The epithelial cells are joined together by protoplasmic 

 bridges, which are best seen in horizontal sections of the 

 epithelial layer i. e., cross-sections of the cells. Between the 

 bridges are spaces which can be demonstrated by treatment 

 with silver nitrate. They are filled with the so-called cement 

 substance. The main function of the intestinal epithelium is 



