DEVELOPMENT OF THE LARGE INTESTINE 221 



fewer glands present. For the first time, the muscularis muco- 

 sae becomes visible, and the glands in places pierce it. In the 

 tip of the vermiform process the epithelial tube is expanded to 

 a diameter of 1.7 mm., in comparison to 0.6 mm. at its base. 

 The villi have practically disappeared, only very slight eleva- 

 tions being left in places. The glands are similar in form, but 

 farther apart than those of the base. In places the muscularis 

 mucosae can be seen, but it is not well differentiated as yet. 



In an embryo of 200 mm. the epithelial tube of the base of 

 the vermiform process (fig. 28), although its diameter is about 

 the same (1.6 mm.), is quite different from that of the preced- 

 ing stage. The villi have almost everywhere entirely disap- 

 peared. The glands are of various size, some of the swollen 

 ones being 0.13 to 0.14 mm. broad. Most of these extend down 

 only to the muscularis mucosae, others have pushed into it and 

 cause it to bulge outward, while still others have pierced it. In 

 some places the swollen ends of glands appear as cysts, entirely 

 cut off from the surface epithelium (figs. 10 and 28). Some cysts 

 appear to be entirely surrounded by a thin stratum of smooth 

 muscle derived from the muscularis mucosae. The epithelium 

 lining the cysts shows various stages of degeneration. In some 

 it appears almost similar to the surface epithelium. In others 

 only that part of the epithelium lining the base of the cyst is 

 similar to that of the surface, while the upper portion, that is, 

 that portion of the cyst which had formerly been the neck of 

 the gland, has an epithelium which is much thinner and com- 

 posed largely of broken down nuclei and fragments of cell 

 protoplasm. In other cysts, degeneration has involved all the 

 cells of the epithelium, but those in the upper end again show 

 a more advanced stage of deterioration. Still other cysts are 

 of smaller size and have their epithelia reduced to a thin line. 



Stohr ('98) and Nagy ('11) found epithelial cysts of the kind 

 described in the vermiform process of human embryos. Accord- 

 ing to Stohr the epithelium of the cut off glands becomes poorer 

 and poorer in goblet cells and begins to degenerate. The cyst 

 itself becomes filled with degenerative products, and as the 

 epithelium gradually goes to pieces the walls collapse. He 



