Numerous microscopic, tubular glands are present in mucosa of stomach. Parietal cells are present in the epithelium of gastric glands and are most numerous on their side walls. They are also called oxyntic cells because they stain strongly with eosin. They secrete hydrochloric acid and castle intrinsic factor (essential for absorption of vitamin $B_{12})$. HCl maintains a strongly acidic pH of about 1.5 to 2 .5 in the stomach. This kills bacteria as well as other harmful organisms that may be present along with food