English: Comparison of stomach glandular regions from several mammalian species. Yellow: esophagus; green: aglandular epithelium; purple: cardiac glands; red: gastric glands; blue: pyloric glands; dark blue: duodenum. Frequency of glands may vary more smoothly between regions than is diagrammed here. Asterisk (ruminant) represents the omasum, which is absent in Tylopoda (Tylopoda also has some cardiac glands opening onto ventral reticulum and rumen). Many other variations exist among the mammals.