Pineal gland 285152 225549583 2008-07-14T07:18:44Z VolatileChemical 264030 /* Cultures, philosophies and mythologies */ {{Infobox Anatomy | Name = Pineal gland | Latin = glandula pinealis | GraySubject = 276 | GrayPage = 1277 | Image = illu_endocrine_system.jpg | Caption = Endocrine system | Image2 = Illu_pituitary_pineal_glands.jpg | Caption2 = Diagram of pituitary and pineal glands. | Precursor = | System = | Artery = [[superior cerebellar artery]] | Vein = | Nerve = | Lymph = | MeshName = Pineal+gland | MeshNumber = | DorlandsPre = g_06 | DorlandsSuf = 12392585 | }} The '''pineal gland''' (also called the '''pineal body''', '''epiphysis cerebri''', or '''epiphysis''') is a small [[endocrine system|endocrine]] gland in the vertebrate [[brain]]. It produces [[melatonin]], a hormone that affects the modulation of wake/sleep patterns and photoperiodic (seasonal) functions.<ref>{{cite journal | author = Macchi M, Bruce J | title = Human pineal physiology and functional significance of melatonin | journal = Front Neuroendocrinol | volume = 25 | issue = 3-4 | pages = 177–95 | year = 2004 | pmid = 15589268 | doi = 10.1016/j.yfrne.2004.08.001}}</ref><ref name="Arendt2005">{{cite journal |author=Arendt J, Skene DJ |title=Melatonin as a chronobiotic |journal=Sleep Med Rev |volume=9 |issue=1 |pages=25–39 |year=2005 |pmid=15649736 | quote = Exogenous melatonin has acute sleepiness-inducing and temperature-lowering effects during 'biological daytime', and when suitably timed (it is most effective around dusk and dawn) it will shift the phase of the human circadian clock (sleep, endogenous melatonin, core body temperature, cortisol) to earlier (advance phase shift) or later (delay phase shift) times. |doi=10.1016/j.smrv.2004.05.002 }}</ref> It is shaped like a tiny pine cone, and is located near the center of the brain, between the two [[cerebral hemisphere|hemisphere]]s, tucked in a groove where the two rounded [[thalamus|thalamic bodies]] join. ==Location== The pineal gland is a reddish-gray body about the size of a [[pea]] (8 [[millimetre|mm]] in humans), located just rostro-dorsal to the [[superior colliculus]] and behind and beneath the [[stria medullaris]], between the laterally positioned [[thalamic bodies]]. It is part of the [[epithalamus]]. The pineal gland is a midline structure, and is often seen in plain [[skull]] [[X-ray]]s, as it is often [[calcification|calcified]]. ==Structure and composition== The pineal body consists in humans of a lobular [[parenchyma]] of [[pinealocytes]] surrounded by [[connective tissue]] spaces. The gland's surface is covered by a [[pial]] capsule. The pineal gland consists mainly of pinealocytes, but four other [[cell (biology)|cell]] types have been identified. {| class="wikitable" | '''Cell type''' || '''Description''' |- | [[pinealocyte]]s || The pinealocytes consist of a cell body with 4-6 processes emerging. They produce and secrete [[melatonin]]. The pinealocytes can be stained by special silver impregnation methods. |- | [[interstitial cell]]s || Interstitial cells are located between the pinealocytes. |- | [[perivascular]] [[phagocyte]] || Many capillaries are present in the gland, and perivascular phagocytes are located close to these blood vessels. The perivascular phagocytes are antigen presenting cells. |- | pineal [[neuron]]s || In higher vertebrates neurons are located in the pineal gland. However, these are not present in rodents. |- | [[peptide]]rgic neuron-like cells || In some species, neuronal-like peptidergic cells are present. These cells might have a paracrine regulatory function. |} The pineal gland receives a [[sympathetic]] innervation from the [[superior cervical ganglion]]. However, a [[parasympathetic]] innervation from the [[sphenopalatine]] and otic ganglia is also present. Further, some nerve fibers penetrate into the pineal gland via the pineal stalk (central innervation). Finally, neurons in the [[trigeminal ganglion]] innervates the gland with nerve fibers containing the neuropeptide, [[PACAP]]. Human follicles contain a variable quantity of gritty material, called [[corpora arenacea]] (or "acervuli", or "brain sand"). Chemical analysis shows that they are composed of [[calcium phosphate]], [[calcium carbonate]], [[magnesium phosphate]], and [[ammonium phosphate]].<ref>{{cite journal | author = Bocchi G, Valdre G | title = Physical, chemical, and mineralogical characterization of carbonate-hydroxyapatite concretions of the human pineal gland | journal = J Inorg Biochem | volume = 49 | issue = 3 | pages = 209–20 | year = 1993 | pmid = 8381851 | doi = 10.1016/0162-0134(93)80006-U}}</ref> Recently, calcite deposits have been described as well.<ref>{{cite journal | author = Baconnier S, Lang S, Polomska M, Hilczer B, Berkovic G, Meshulam G | title = Calcite microcrystals in the pineal gland of the human brain: first physical and chemical studies | journal = Bioelectromagnetics | volume = 23 | issue = 7 | pages = 488–95 | year = 2002 | pmid = 12224052 | doi = 10.1002/bem.10053}}</ref> ==Miscellaneous anatomy== [[Pinealocyte]]s in many non-mammalian [[vertebrate]]s have a strong resemblance to the [[photoreceptor]] cells of the [[eye]]. Some evolutionary biologists believe that the vertebrate pineal cells share a common [[evolution]]ary ancestor with retinal cells.<ref>{{cite journal | author = Klein D | title = The 2004 Aschoff/Pittendrigh lecture: Theory of the origin of the pineal gland--a tale of conflict and resolution | journal = J Biol Rhythms | volume = 19 | issue = 4 | pages = 264–79 | year = 2004 | pmid = 15245646 | doi = 10.1177/0748730404267340}}</ref> In some vertebrates, exposure of the pineal to light can directly set off a chain reaction of enzymatic events which regulate [[circadian rhythm]]s.<ref>Moore RY, Heller A, Wurtman RJ, Axelrod J. Visual pathway mediating pineal response to environmental light. ''Science'' 1967;155(759):220–3. PMID 6015532</ref> In humans and other mammals, this function is served by the [[retinohypothalamic tract|retinohypothalamic]] system that sets the rhythm within the [[suprachiasmatic nucleus]]. Cultural and social interactions produce exposures to artificial light that influence the setting of the suprachiasmatic clock. Some early vertebrate fossil skulls have a pineal [[foramen]]. This corroborates with the physiology of the modern [[lamprey]], [[tuatara]], and some other vertebrates. ==Function== The pineal gland was originally believed to be a "[[vestigial]] remnant" of a larger organ (much as the [[Vermiform appendix|appendix]] was thought to be a vestigial digestive organ). Aaron Lerner and colleagues at [[Yale University]] discovered that melatonin, the most potent compound then known to lighten frog skin, was present in the highest concentrations in the pineal.<ref>{{cite journal | author = Lerner AB, Case JD, Takahashi Y | title = Isolation of melatonin and 5-methoxyindole-3-acetic acid from bovine pineal glands | journal = J Biol Chem | volume = 235 | pages = 1992–7 | year = 1960 | pmid = 14415935}}</ref> [[Melatonin]] is a derivative of the [[amino acid]] [[tryptophan]], which also has other functions in the [[central nervous system]]. The production of melatonin by the pineal gland is stimulated by darkness and inhibited by light.<ref>{{cite journal | author = Axelrod J | title = The pineal gland | journal = Endeavour | volume = 29 | issue = 108 | pages = 144–8 | year = 1970 | pmid = 4195878}}</ref> Photosensitive cells in the retina detect light and directly signal the [[suprachiasmatic nucleus]] (SCN), entraining it to the 24 hour clock. Fibers project from the SCN to the paraventricular nuclei (PVN), which relay the circadian signals to the [[spinal cord]] and out via the sympathetic system to [[superior cervical ganglia]] (SCG), and from there into the pineal gland. The function(s) of melatonin in humans is not clear; it is commonly prescribed for the treatment of [[circadian rhythm sleep disorder]]s. The pineal gland is large in children, but shrinks at [[puberty]]. It appears to play a major role in sexual development, [[hibernation]] in animals, metabolism, and seasonal breeding. The abundant melatonin levels in children is believed to inhibit sexual development, and pineal tumors have been linked with [[precocious puberty]]. When puberty arrives, melatonin production is reduced. [[Calcification]] of the pineal gland is typical in adults. Pineal [[cytostructure]] seems to have evolutionary similarities to the retinal cells of chordates.<ref>{{cite journal | author = Klein D | title = The 2004 Aschoff/Pittendrigh lecture: Theory of the origin of the pineal gland--a tale of conflict and resolution | journal = J Biol Rhythms | volume = 19 | issue = 4 | pages = 264–79 | year = 2004 | pmid = 15245646 | doi = 10.1177/0748730404267340}}</ref> Modern [[bird]]s and [[reptile]]s have been found to express the [[phototransduction|phototransducing]] [[pigment]] [[melanopsin]] in the pineal gland. Avian pineal glands are believed to act like the [[suprachiasmatic nucleus]] in [[mammal]]s.<ref>{{cite journal | author = Natesan A, Geetha L, Zatz M | title = Rhythm and soul in the avian pineal | journal = Cell Tissue Res | volume = 309 | issue = 1 | pages = 35–45 | year = 2002 | pmid = 12111535 | doi = 10.1007/s00441-002-0571-6}}</ref> Studies suggest that in rodents the pineal gland may influence the actions of recreational drugs, such as cocaine,<ref>{{cite journal | author = Uz T, Akhisaroglu M, Ahmed R, Manev H | title = The pineal gland is critical for circadian Period1 expression in the striatum and for circadian cocaine sensitization in mice | journal = Neuropsychopharmacology | volume = 28 | issue = 12 | pages = 2117–23 | year = 2003 | pmid = 12865893 | doi = 10.1038/sj.npp.1300254}}</ref> and [[antidepressant]]s, such as fluoxetine (Prozac),<ref>{{cite journal | author = Uz T, Dimitrijevic N, Akhisaroglu M, Imbesi M, Kurtuncu M, Manev H | title = The pineal gland and anxiogenic-like action of fluoxetine in mice | journal = Neuroreport | volume = 15 | issue = 4 | pages = 691–4 | year = 2004 | pmid = 15094477 | doi = 10.1097/00001756-200403220-00023 }}</ref> and its hormone melatonin can protect against [[neurodegeneration]].<ref>{{cite journal | author = Manev H, Uz T, Kharlamov A, Joo J | title = Increased brain damage after stroke or excitotoxic seizures in melatonin-deficient rats | journal = FASEB J | volume = 10 | issue = 13 | pages = 1546–51 | year = 1996 | pmid = 8940301}}</ref> ==Cultures, philosophies and mythologies== The secretory activity of the pineal gland has only relatively recently become understood. Historically, its location deep in the brain suggested to philosophers that it possessed particular importance. This combination led to its being a "mystery" gland with myth, superstition and [[metaphysics|metaphysical]] theories surrounding its perceived function. [[René Descartes]], who dedicated much time to the study of the pineal gland,<ref>[http://plato.stanford.edu/entries/pineal-gland/ Descartes and the Pineal Gland] ([[Stanford Encyclopedia of Philosophy]])</ref> called it the "seat of the [[soul]]".<ref>Descartes R. ''Treatise of Man''. New York: Prometheus Books; 2003. ISBN 1-59102-090-5</ref> He believed that it was the point of connection between the intellect and the body.<ref>Descartes R. "The Passions of the Soul" excerpted from "Philosophy of the Mind", Chalmers, D. New York: Oxford University Press, Inc.; 2002. ISBN-13 978-0-19-514581-6</ref> This was in part because of his belief that it is 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. Another theory was that the pineal operated as a valve releasing fluids, thus the position taken during deep thought, with the head slightly down meeting the hand, was an allowance for the opening of these 'valves'. The pineal gland is occasionally associated with the sixth [[chakra]] (also called [[Ajna]] or the [[third eye]] chakra in [[yoga]]) or sometimes the Seventh (Crown) chakra. It is believed by some to be a dormant organ that can be awakened to enable [[telepathy|telepathic]] communication.{{Fact|date=December 2007}} The pineal gland has relevance for [[Discordianism]] which is rooted in [[California]]n psychedelic culture where it is said to be the connection to the goddess Eris{{Fact|date=June 2008}} (although in this case it is likely a satire of the mysticism attributed to it in the aforementioned examples). Writers such as [[Madame Blavatsky]] and [[Alice Bailey]], considered early proponents of the [[new age]] movement, use the pineal-eye as a key element in their spiritual world-view...(see [[Alice Bailey]]: "[[A Treatise on White Magic]]", [[Madame Blavatsky]]: "[[The Secret Doctrine]]") The notion of a 'pineal-eye' is also crucial to the philosophy of the seminal French writer [[Georges Bataille]], which is analyzed at length by literary scholar Denis Hollier in his study ''Against Architecture''.<ref>Hollier, D, ''Against Architecture: The Writings of Georges Bataille'', trans. Betsy Wing, MIT, 1989.</ref> <blockquote>"But the head has a hole in it. The pineal eye, the organ of not-knowing, is the undoing of science. If science thought up man, the pineal eye unthinks him, spends him extravagantly, makes him lose the reserve in which, at the summit, from his head position, he was guarding himself."<ref>(p129; ''Against Architecture'')</ref></blockquote> In this work Hollier discusses how Bataille uses the concept of a 'pineal-eye' as a reference to a blind-spot in Western rationality. <blockquote>"When I carefully seek out, in deepest anguish, some strange absurdity, an eye opens at the top, in the middle of my skull. This eye opening up onto the sun in all its glory, to contemplate it in its nakedness, privately, is not the work of my reason: it is a cry escaping from me. For at the moment when the flash blinds me I am the splintering brilliance of a shattered life, and this life - agony and vertigo - opening up onto an infinite void, bursts and exhausts itself all at once in this void."<ref>''L'Experience interieure'', p101 (trans. Leslie A Boldt: The Inner Experience) Albany: SUNY Press</ref></blockquote> The pineal gland also plays a role in the transformation of a scientist into a grotesque monster in the [[H. P. Lovecraft]]-inspired film [[From Beyond (film)|From Beyond]]. In ''[[Fear and loathing in Las Vegas]]'' by [[Hunter S. Thompson]], [[Raoul Duke]] and [[Oscar Zeta Acosta|his attorney]] amuse themselves by tricking a clueless police officer into beliveing that gangs of drug freaks in Los Angeles routinely decapitate suburban families to harvest their pineal glands.<ref>Thompson "Fear and Loathing In Las Vegas", p 147, New York: Harper</ref></blockquote> Later in the novel, the attorney frightens an [[adrenochrome]]-crazed Duke with various increasingly fantastical health defects that might result, should one eat extract of pineal gland as a psychoactive. ==Additional images== <gallery> Image:Gray715.png|Mesal aspect of a brain sectioned in the median sagittal plane. Image:Gray716.png|Dissection showing the ventricles of the brain. Image:Gray719.png| Hind- and mid-brains; postero-lateral view. Image:Gray720.png|Median sagittal section of brain. </gallery> ==References== {{Reflist|2}} ==External links== {{Wiktionary|pineal gland}} * {{BrainMaps|pineal%20gland}} * {{BrainInfo|hier|280}} * {{BUHistology|14401loa}} - "Endocrine System: pineal gland " * {{AnatomyAtlasesMicroscopic|15|296}} * Images of Pineal region http://rad.usuhs.edu/medpix/medpix.html?mode=image_finder&action=search&srchstr=pineal&srch_type=all#top * http://isc.temple.edu/neuroanatomy/lab/atlas/pdhn/ {{Diencephalon}} {{Endocrine system}} [[Category:Glands]] [[Category:Endocrine system]] [[Category:Head and neck]] [[Category:Sleep physiology]] [[Category:Circadian rhythms]] [[bs:Epifiza]] [[bg:Епифиза]] [[cs:Šišinka]] [[de:Zirbeldrüse]] [[dv:ޕިނިއަލް ގްލޭންޑް]] [[el:Επίφυση]] [[es:Glándula pineal]] [[fr:Glande pinéale]] [[gl:Glándula pineal]] [[ko:송과선]] [[it:Ghiandola pineale]] [[he:בלוטת האצטרובל]] [[la:Glandula pinealis]] [[lt:Kankorėžinė liauka]] [[mk:Епифиза]] [[nl:Pijnappelklier]] [[ja:松果体]] [[no:Konglekjertelen]] [[pl:Szyszynka]] [[pt:Glândula pineal]] [[ru:Эпифиз]] [[simple:Pineal gland]] [[sk:Šuškovité teliesko]] [[sl:Češerika]] [[fi:Käpyrauhanen]] [[sv:Tallkottkörteln]] [[uk:Епіфіз]]