Histology of Stomach

In transverse section of the stomach of frog four regions can be seen from outside inward as follows:- (1) Serosa, (2) muscular coat (3) Submucosa and (4) mucosa. The serosa or serous coat is formed of wavy margined squamose epithelial layer to the exterior and connective tissue to the interior. Next to the serosa is the muscular coat made up of non-striated muscles. The muscular coat consists of an outer thin layer of longitudinally arranged muscles fibres called longitudinal muscles and a very thick layer of circular muscles. Between the longitudinal and circular muscles layers there is thin network of nerve fibres. The Submucosa is a layer of connective tissue having blood vessels and nerve fibres whose branches extend in the mucosa internally and muscular coat externally. The mucosa or mucous membrane consists of an outer muscularis mucosa and an inner glandular epithelium separated by a thin layer of connective tissue. The muscularis mucosa consists of outer longitudinal muscles layer and inner circular muscle layer. It is very well developed in stomach and shows several longitudinal folds. The glandular epithelium surrounding the lumen of stomach forms a large number of simple or branched tubular gastric glands, each of which opens into the lumen of stomach by a minute pore. The tube of gastric glands is lined by more or less columnar epithelial cells that secretes water types of cells:-(1) Peptic cells secreting pepsinogen and (2) round or oval oxyntic cells secreting HCI.