<Tr> <Th> FMA </Th> <Td> 62033 </Td> </Tr> <Tr> <Td_colspan="2"> Anatomical terms of neuroanatomy (edit on Wikidata) </Td> </Tr> <P> The pineal gland, also known as the conarium or epiphysis cerebri, is a small endocrine gland in the vertebrate brain . The pineal gland produces melatonin, a serotonin derived hormone which modulates sleep patterns in both circadian and seasonal cycles . The shape of the gland resembles a pine cone, hence its name . The pineal gland is located in the epithalamus, near the center of the brain, between the two hemispheres, tucked in a groove where the two halves of the thalamus join . </P> <P> Nearly all vertebrate species possess a pineal gland . The most important exception is a primitive vertebrate, the hagfish . Even in the hagfish, however, there may be a "pineal equivalent" structure in the dorsal diencephalon . The lancelet Branchiostoma lanceolatum, the nearest existing relative to vertebrates, also lacks a recognizable pineal gland . The lamprey (another primitive vertebrate), however, does possess one . A few more developed vertebrates lost pineal glands over the course of their evolution . </P>

The hormone that the pineal gland secretes is