The orobasal organ (of Ackerknecht): A bizarre structure of the mammalian oral cavity.

Vestigial organs are considered to have lost most or all of their functions through evolution. However, these structures can give insights into the phylogenetic history of species. Additionally, vestigial organs can be of clinical importance, since these structures might be confused with pathologies. The orobasal organ of Ackerknecht was discovered by and named after the veterinary anatomist Eberhard Ackerknecht. In 1912, he described morphologically highly variable epithelial invaginations behind the lower medial incisors in different mammalian species. The orobasal organ is considered a rudimentary structure without physiological function, but the evolutionary history of the orobasal organ remains unknown, so far. In this review, we sum up the actual knowledge about the orobasal organ and discuss possible origins of this structure. With this review, we hope to increase awareness of this anatomical structure, and thereby decrease the risk of confusion with a pathological condition like oral cancer.