114: NOKMAL HISTOLOGY. 



acid cells. The pyloric glands are distributed upon the pyloric third 

 of the stomach and are of the compound tubular variety. They are 

 not provided with acid cells. They have a wide duct which leads 

 to the narrow lumens of the tubular branches. The stroma consists 

 of connective tissue supplied with capillaries and lymphatics. The 

 muscularis mucosw consists of a double layer of smooth muscle, an 

 inner circular, and an outer longitudinal. 



The sub-mucosa is composed of loosely-woven bundles of elastic 

 tissue, containing blood-vessels and nerves. Upon its outer surface 

 there are alternate elevations and depressions. These give rise to 

 the so-called rugae and depressions of the stomach wall. 



The muscular coat consists of an inner circular layer and an 

 outer longitudinal stratum of smooth muscle. At the cardiac end 

 there is also a middle oblique layer. 



The serous coat consists of fibrous tissue and elastic fibres, lined 

 superficially with a single layer of endothelium. 



Laboratory exercise No. 34. The stomach. Fix in corrosive sublimate 

 solution, embed in celloidin, and stain with hsematoxylin and eosin, 

 method No. 8. Use H. P. and L. P. First demonstrate the four coats; 

 then observe the internal lining- of columnar cells with their basement 

 membrane. Locate and study the peptic and pyloric glands. Observe 

 the stroma and muscularis mucosse; also distinguish between the circu- 

 lar and longitudinal muscle layers. How does the serous coat differ in 

 appearance from the sub-mucosa? Drawings. 



THE SMALL INTESTINE. 



The small intestine comprises the duodenum, jejunum, and ileum. 

 These parts differ but slightly in general structure. There are the 

 four characteristic coats mucosa, sub-mucosa, muscular coat, and 

 serous coat. 



The mucosa consists of the following structures: (1) A single 

 layer of columnar epithelial cells, which cover the surfaces of conical 

 elevations which stud the intestine, the villi; (2) the basement 

 membrane, which supports the epithelium; (3) the stroma, or 

 tunica propria, which forms conical projections, the villi. It con- 

 sists chiefly of connective tissue. Each villus is supplied, superfi- 

 cially, with a capillary network, and through its center extends a 

 lacteal. (4) The muscularis mucosw consists of a longitudinal layer 

 with occasional circular fibres of smooth muscle. 



