Stomach or compound racemose resembling the duodenal Brunner's glands The "fundic glands", are found in the fundus and body of the stomach. They are simple almost straight tubes, two or more of which open into a single duct. They secrete hydrochloric acid (HCl) and intrinsic factor. The "pyloric glands" are located in the antrum of the pylorus. They secrete gastrin produced by their G cells. About 20,000 protein coding genes are expressed in human cells and nearly 70% of these genes are expressed in the normal stomach. Just over 150 of these genes are more specifically expressed in the stomach compared
Stomach to other organs, with only some 20 genes being highly specific. The corresponding specific proteins expressed in stomach are mainly involved in creating a suitable environment for handling the digestion of food for uptake of nutrients. Highly stomach-specific proteins include GKN1, expressed in the mucosa; pepsinogen PGC and the lipase LIPF, expressed in chief cells; and gastric ATPase ATP4A and gastric intrinsic factor GIF, expressed in parietal cells. In early human embryogenesis, the ventral part of the embryo abuts the yolk sac. During the second week of development, as the embryo grows, it begins to surround parts of the sac.