262 



THE ORGANS 



of the cell. A peculiarity of these cells is the striated free border, con- 

 tiguous free borders uniting to form the so-called cuticidar membrafie 

 (Fig. 167, c). By means of special technic these striations can be re- 

 solved into delicate parallel lying rods or fibrils. They have been inter- 

 preted by some as marking channels through the cuticle, by others as a 

 fibrillar arrangement of the protoplasm. Scattered among the col- 

 umnar cells are mucous or goblet cells (Figs. 166 and 167, b). These 

 vary in appearance according to the amount of secretion which they 

 contain. A cell at the beginning of secretion contains only a small 

 amount of mucus near its free border. As secretion increases the 



% 



V«/. 





X X 







'*A 



WW X ^^M 







/ — . 



8- 



Fig. 163. — Vertical Longitudinal Section of Human Jejunum (X16) (Stohr), includ- 

 ing two valvulae conniventes. a, Villi, in many of which the stroma has shrunken away 

 from the epithelium leaving a clear space, XX. Lying free in the lumen of the gut are 

 seen sections of villi cut in various directions, b, Epithelium; c, stroma; d, cr\'pts of 

 Lieberkiihn; X, soHtary lymph nodule with germinal centre; e, tissue of sub mucosa 

 forming centre of one of the valvule conniventes;/, submucosa; g, inner circular layer 

 of muscle; k, outer longitudinal layer of muscle; i, Auerbach's plexus;/, serous coat. 



mucus gradually replaces the cytoplasm until the latter is represented 

 only by a crescentic mass containing a flattened nucleus and pressed 

 against the basement membrane. The cell now discharges its mucus 

 upon the free surface. The goblet cells possess no thickened border, 

 appearing, when seen from the surface, as openings surrounded on 

 all sides by the cuticulae of the adjacent columnar cells. Opinions 



