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Pineal gland
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Pineal gland

The pineal gland, or epiphysis, is a small endocrine gland located near the middle of the brain.

The pineal body is located above the superior colliculus and behind and beneath the stria medullaris, between the laterally positioned thalamic bodies. The pineal body is part of the epithalamus.

It is responsible for the production of melatonin, which has a role in circadian rhythm. Melatonin is a derivative of the amino acid tryptophan. The production of melatonin by the pineal gland is stimulated by darkness and inhibited by light. Light can be detected by the suprachiasmatic nucleus (SCN) which has directs connections to the retina. Fibers extends from SCN to the spinal cord into superior cervical ganglia and from there into the pineal gland.

It has been found that the pineal gland manufactures trace amounts for the psychedelic chemical, dimethyltryptamine, or DMT. The purpose of this endogeous chemical in the human brain is believed to play a role in dreaming and possibly near-death experiences and other mystical states. It has been suggested by the researcher Jace Callaway that DMT is connected with visual dreaming.

The pineal gland consists mainly of pinealocytes, but four other cell types have been identified: interstitial cells, perivascular phagocyte, pineal neurons and peptidergic neuron-like cells.

The pineal gland is a midline structure and is often seen in plain skull X-rays as it is often calcified.

It is occasionally referred to as the "third eye" in occult religions, and is believed by some to be a dormant organ that can be awakened to enable telepathic communication.

In fact ancient amphibians such as Ichthyostega, which existed in the Late Devonian Period, have an orifice on the top of the skull through which the pineal gland once was exposed and received light input. Over the course of time and for unknown reasons, the pineal migrated into the skull of later tetrapods and the skull orifice sealed.

Endocrine system
Adrenal gland; - Corpus luteum; - Hypothalamus - Ovaries - Pancreas - Parathyroid gland; - Pineal gland; - Pituitary gland; - Testes - Thyroid gland;