The Pineal Gland

The pineal gland is a small reddish-gray body and is about 8 mm in size for humans. It's located between the laterally positioned thalamic bodies and it is part of the epithalamus. The pineal gland consists mainly of pinealocytes, but it has been identified with four other types of cell types too. The pineal body does have nervous tissue, and consists of follicles lined by epithilium and contianed by connective tissue. These follicles contain a large quantity of gritty material, composed of phosphate, carbonate, and ammonia.

The function of the pineal gland is to be responsible for the production of melatonin, which has a role in regulating circadian ryhtms. The production of melatonin by the pineal gland is stimulated by darkness and inhibited by light. Light can be detected by the SCN which has direct connections to the retina. Fibers extend from the SCN to the spinal cord then into the SCG and from there into the pineal gland.

The pineal gland also contains a substance which if injected and causes fall of blood-pressure. It's possible that the gland holds an internal secretion in children that inhibits the development of the reproductive glands, since the invasion of the gland in children, by growths which destroy the glandular tissue, increased growth of the skeleton and precocious mentality.

Additionally, it has been found that the pineal gland manufactures trace amounts something called DMT. This chemical in the human brain plays a role in dreaming and possibly near-fatal experiences and other mythical states.

Mythology

The pineal gland was the last endocrine gland to have its function discovered. Its location deep in the brain indicated its importance. This combination led to it being a "mystery" gland with superstition and even metaphysical theories surrounding its function.

oh and The pineal gland is occasionally referred to as the "third eye" in some religions, and also thought by some to be a dormant organ that can be awakened for telepathic communication.