Epiphysis cerebri

epiphysis cerebri - a small endocrine gland in the brain; situated beneath the back part of the corpus callosum; secretes melatonin

pineal body, pineal gland, epiphysis

ductless gland, endocrine gland, endocrine - any of the glands of the endocrine system that secrete hormones directly into the bloodstream.

The pineal gland (also called the pineal body, epiphysis cerebri, epiphysis, conarium or the "third eye") is a small endocrine gland in the vertebrate brain. It produces the serotonin derivative melatonin, a hormone that affects the modulation of wake/sleep patterns and seasonal functions. Its shape resembles a tiny pine cone (hence its name), and it is located near the centre of the brain, between the two hemispheres, tucked in a groove where the two rounded thalamic bodies join.

Nearly all vertebrate species possess a pineal gland. The most important exception is the hagfish, which is often thought of as the most primitive type of vertebrate. Even in the hagfish, though, there may be a "pineal equivalent" structure in the dorsal diencephalon. The lancelet amphioxus, the nearest existing relative to vertebrates, also lacks a recognizable pineal gland. The lamprey, however (considered almost as primitive as the hagfish), does possess one.A few "higher" types of vertebrates, including the alligator, lack pineal glands because they have been lost over the course of evolution.

 A mutation of this gland is responsible for Psionic abilities in humanoid beings. The HPI measures (among other things) the secretion of dual existence super exotics.