HA22 illustrates the changes that take place at the transition from the stomach to the small intestine. The pyloric region has a greater diameter than the duodenum in this image (the duodenum is left and the pyloric region is right of the pyloric sphincter, ps, HA22). At this low magnification, you can see that the stomach epithelium is the same height, but the duodenal epithelium extends villi into the lumen.