THE STRUCTURE OF THE STOMACH. 



169 



The mucous membrane is a soft, thick layer, generally somewhat 

 corrugated in the empty condition of the organ. Its thickness is 

 mainly due to the fact that it is largely made up of long tubular glands, 

 which open upon the inner surface. Between the glands the mucous 

 membrane is formed of areolar with much lymphoid tissue. Externally 

 it is bounded by the muscularis mucosw, which consists of an external 

 longitudinal and an inner circular layer of plain muscular fibres. The 

 glands are formed of a basement-membrane lined with epithelium. 

 Each gland consists of three or four secreting tubules, which open 

 towards the surface into a larger common tube, the duct of the gland. 

 The duct is in all cases lined by columnar epithelium of the same 

 character as that which covers the inner surface of the mucous mem- 

 brane, but the epithelium of the secreting tubules is different from 

 this, and also differs somewhat in the glands of the cardiac and pyloric 

 regions of the organ. 



FIG. 199. SECTION OF THE GASTRIC MUCOUS MEMBRANE TAKEN ACROSS THE 

 DIRECTION OF THE GLANDS (CARDIAC PART). 



6, basement membrane ; c, central cells ; o, oxyntic cells ; ?, retiform tissue (with 

 sections of blood-capillaries) between the glands. 







In the cardiac glands (fig. 197) the secreting tubules are long, and 

 the duct short. The epithelium of the tubules is composed of two kinds 

 of cells. Those of the one kind, which form a continuous lining to the 

 tubule, are somewhat polyhedral in shape, and in stained sections look 

 clearer and smaller than the others, but in the fresh glands, and in 

 osmic preparations, they appear filled with granules (fig. 198). 1 These 

 cells are believed to secrete the pepsin of the gastric juice, and are 



lf rhe granules are most numerous at the inner part of the cell, a small outer 

 zone being left clear. After prolonged activity this outer zone increases in size 

 while the granules diminish in number as in the analogous cases of the pancreas 

 and parotid glands. 



