The pineal gland (pronunciation: 'pI-nE-&l, pI-'), or ''epiphysis'', is a small endocrine system gland. It is located near the center of the brain, between the two hemispheres and near the central switching point of the thalamus. It is also referred to as the pineal body. == Location == The pineal gland is a small (8 Millimetre in human) reddish-gray body located above the superior colliculus and behind and beneath the stria medullaris, between the laterally positioned thalamus. It is part of the epithalamus. The pineal gland is a midline structure and is often seen in plain skull X-rays as it is often calcified. == Structure and composition == 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 body does not have Nervous system tissue, and consists of follicles lined by epithelium and enveloped by connective tissue. These follicles contain a variable quantity of gritty material, composed of phosphate and carbonate of calcium, phosphate of magnesium and ammonia, and a little animal matter. == Function == It is responsible for the production of melatonin, which has a role in regulating the 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 direct connections to the retina. Fibers extend from the SCN to the spinal cord via the periventricular nuclei (PVN) into superior cervical ganglia (SCG) and from there into the pineal gland. In fact, ancient amphibians such as ''Ichthyostega'', which existed in the Late Devonian Period, had an orifice on the top of the skull through which the pineal gland was exposed and received light input. Over the course of time and for unknown reasons, the pineal gland migrated into the skull of later tetrapods and the skull orifice sealed. Modern birds and reptiles have been found to express the phototransducing pigment melanopsin in the pineal gland. Avian pineal glands are believed to act like the suprachiasmatic nucleus in mammals. It also contains a substance which if injected intravenously causes fall of blood-pressure. It seems probable that the gland furnishes an internal secretion in children that inhibits the development of the reproductive glands since the invasion of the gland in children, by pathological growths which practically destroy the glandular tissue, results in accelerated development of the sexual organs, increased growth of the skeleton and precocious mentality. Additionally, it has been found that the pineal gland manufactures trace amounts of the psychedelic chemical dimethyltryptamine, or DMT. 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. == Mythology == The pineal gland was the last endocrine gland to have its function discovered. Thus, it was a 'mystery' gland for an extended period. At the same time, its location deep in the brain seemed to indicate that its (unknown) function was important. This combination led to a number of mythologies involving the function of the pineal gland. Rene Descartes called the pineal gland the "seat of the soul", believing it was unique in the anatomy of the human brain in being a structure not duplicated on the right and left sides. This observation is not true, however; under a microscope one finds the pineal gland is divided into two fine hemispheres. The pineal gland is occasionally referred to as the "third eye" in occult religions, and the brow Ajna in yoga, and is believed by some to be a dormant organ that can be awakened to enable telepathy communication. == See also == * Discordianism for the relevance of the pineal gland in this :Category:Joke religions. Endocrine system Head and neck
I have no idea what Gray's Anatomy means by "animal matter" in the second paragraph of the Pineal gland#Structure and composition. -- User:Phyzome User:Phyzome is User talk:Phyzome 22:44, 2004 Dec 8 (UTC) I think the ''animal matter'' refers to a complex of proteins. The associated anatomical structure is really peripherial. I guess removing it should be the best for the article... User:moosattack == Images == I think this article is in desperate need of images. The description of where this important gland sounds like ancient Greek to someone that knows nothing about the brain and it's anatomy. User:JoeHenzi 18:40, 5 Apr 2005 (UTC) == Blood Pressure == The third paragraph under "Functions" starts with, 'It also contains a substance which if injected intravenously causes fall of blood-pressure.' Is this supposed to refer to the correlation between blood pressure and Melatonin production? The description in "Functions" is vague. Melatonin usally increases potassium channel conductance thereby slowing down the heart rate and possibly relaxing the endothelium (haven't checked this). user:moosattack == pineal cyst == I have a cyst on my pineal gland is that dangerous?
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Pineal gland
The pineal gland (pronunciation: 'pI-nE-&l, pI-'), or ''epiphysis'', is a small endocrine system gland. It is located near the center of the brain, between the two hemispheres and near the central switching point of the thalamus. It is also referred to as the pineal body. == Location == The pineal gland is a small (8 Millimetre in human) reddish-gray body located above the superior colliculus and behind and beneath the stria medullaris, between the laterally positioned thalamus. It is part of the epithalamus. The pineal gland is a midline structure and is often seen in plain skull X-rays as it is often calcified. == Structure and composition == 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 body does not have Nervous system tissue, and consists of follicles lined by epithelium and enveloped by connective tissue. These follicles contain a variable quantity of gritty material, composed of phosphate and carbonate of calcium, phosphate of magnesium and ammonia, and a little animal matter. == Function == It is responsible for the production of melatonin, which has a role in regulating the 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 direct connections to the retina. Fibers extend from the SCN to the spinal cord via the periventricular nuclei (PVN) into superior cervical ganglia (SCG) and from there into the pineal gland. In fact, ancient amphibians such as ''Ichthyostega'', which existed in the Late Devonian Period, had an orifice on the top of the skull through which the pineal gland was exposed and received light input. Over the course of time and for unknown reasons, the pineal gland migrated into the skull of later tetrapods and the skull orifice sealed. Modern birds and reptiles have been found to express the phototransducing pigment melanopsin in the pineal gland. Avian pineal glands are believed to act like the suprachiasmatic nucleus in mammals. It also contains a substance which if injected intravenously causes fall of blood-pressure. It seems probable that the gland furnishes an internal secretion in children that inhibits the development of the reproductive glands since the invasion of the gland in children, by pathological growths which practically destroy the glandular tissue, results in accelerated development of the sexual organs, increased growth of the skeleton and precocious mentality. Additionally, it has been found that the pineal gland manufactures trace amounts of the psychedelic chemical dimethyltryptamine, or DMT. 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. == Mythology == The pineal gland was the last endocrine gland to have its function discovered. Thus, it was a 'mystery' gland for an extended period. At the same time, its location deep in the brain seemed to indicate that its (unknown) function was important. This combination led to a number of mythologies involving the function of the pineal gland. Rene Descartes called the pineal gland the "seat of the soul", believing it was unique in the anatomy of the human brain in being a structure not duplicated on the right and left sides. This observation is not true, however; under a microscope one finds the pineal gland is divided into two fine hemispheres. The pineal gland is occasionally referred to as the "third eye" in occult religions, and the brow Ajna in yoga, and is believed by some to be a dormant organ that can be awakened to enable telepathy communication. == See also == * Discordianism for the relevance of the pineal gland in this :Category:Joke religions. Endocrine system Head and neck
Pineal gland
I have no idea what Gray's Anatomy means by "animal matter" in the second paragraph of the Pineal gland#Structure and composition. -- User:Phyzome User:Phyzome is User talk:Phyzome 22:44, 2004 Dec 8 (UTC) I think the ''animal matter'' refers to a complex of proteins. The associated anatomical structure is really peripherial. I guess removing it should be the best for the article... User:moosattack == Images == I think this article is in desperate need of images. The description of where this important gland sounds like ancient Greek to someone that knows nothing about the brain and it's anatomy. User:JoeHenzi 18:40, 5 Apr 2005 (UTC) == Blood Pressure == The third paragraph under "Functions" starts with, 'It also contains a substance which if injected intravenously causes fall of blood-pressure.' Is this supposed to refer to the correlation between blood pressure and Melatonin production? The description in "Functions" is vague. Melatonin usally increases potassium channel conductance thereby slowing down the heart rate and possibly relaxing the endothelium (haven't checked this). user:moosattack == pineal cyst == I have a cyst on my pineal gland is that dangerous?
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