164 



NORMAL HISTOLOGY. 



plastic threads within the body of the cell. In places, especially over the 

 villi, many of the epithelial elements are engaged in producing mucus and, 

 hence, appear as goblet-cells. Migratory lymphocytes are usually to be 

 seen between the cells, while during digestion the cytoplasm of the latter is 

 often loaded with particles of fat. The oval nuclei occupy the deeper parts 

 of the cells. The tunica propria of the intestinal mucosa resembles lymphoid 

 tissue, since it consists of a delicate connective tissue reticulum containing 

 numerous small round cells similar to lymphocytes. This stroma fills the 



Villus- 



Duct of Brunner's - ySju 

 glands 



Muscularis mucosa 



Brunner's glands 



rypt of Lieberkiilm 



ner's glands 



Serous coat 



Circular muscle 



Longitudinal muscle 



FIG. 203. Transverse section of small intestine (duodenum 1 ), showing general arrangement of coats and 

 the two varieties of glands. X 90. 



spaces between the glands and forms the core of the villi over which the 

 epithelium stretches. The deeper part of the mucosa is occupied by a well- 

 marked muscularis mucosce, composed of an inner circular and an outer 

 longitudinal layer of unstriped muscle. 



The villi are minute projections of the mucosa, barely visible to the 

 unaided eye, whose presence imparts the characteristic velvety appearance to 

 the inner surface of the small intestine. Although found throughout the 

 latter (but absent in the large gut), they are most abundant (20-40 to the 

 sq. mm.) in the duodenum and the jejunum and less numerous (15-30 to 

 the sq. mm. ) in the ileum. In the duodenum they appear close to the 



