1178 



DIGESTIVE SYSTEM 



The vermiform process, however, differs in several important respects (fig. 940). The 

 walls are relatively thick and the lumen small. The solitary lymph nodules are closely packed 

 or confluent (especially in j'oung people). They occupy the greater part of the submucosa, 

 and somewhat resemble the Peyer's patches of the ileum. They, hke all the lymphoid structures 



Fig. 939. — Cross-section of the Large Intestine, a, Mucosa, b, Submucosa. c, Mus- 



cularis. d, Serosa. (Radasch.) 



in general, tend to become atrophied in old age. Fat cells are usually abundant in the sub- 

 mucosa. The muscularis presents an inner circular layer and also a thin but complete outer 

 longitudinal layer. The serosa is typical. The lumen shows a progressive tendency to ob- 

 literation as age advances (Ribbert). This condition is never found in infancy but occurs 



Fig. 940. — Transverse Section of the Human Vermiform Process. (X 20). (Stohr 

 and Lewis, from Sobotta.) Note absence of villi and abundance of Ij-mph nodules. F, Clusters 

 of fat cells in submucosa. Only the inner part of the circular muscle is shown. 



usually only partial) in over 2r> per cent, of adults and in 50 per cent, of all cases over 50 years 

 of age. It is, however, somewhat imcortain whether this represents a normal process. In 

 obliteration, the glands and lymplioid nodules disappear, and the entire mucosa is transformed 

 into an axial mass of fibrous connective tissue. 



The rectum also presents several peculiarities of structure. Attention has already been 



