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Anterior pituitary
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<h2 id="structure">Structure</h2> <p>The <a href="/facts/Pituitary_gland/gdrQyldF">pituitary gland</a> sits in a protective bony enclosure called the <a href="/facts/Sella_turcica/9aSGaHDf">sella turcica</a> (<i>Turkish chair/saddle</i>). It is composed of three lobes: the anterior, intermediate, and posterior lobes. In many animals, these lobes are distinct. However, in humans, the intermediate lobe is but a few cell layers thick and indistinct; as a result, it is often considered part of the anterior pituitary. In all animals, the fleshy, glandular anterior pituitary is distinct from the <a href="/facts/Neural/CDxRKU2U">neural</a> composition of the <a href="/facts/Pars_nervosa/CEXxb9Bp">pars nervosa</a> of the <a href="/facts/Posterior_pituitary/CEXxb9Bp">posterior pituitary</a>. </p><p>The anterior pituitary is composed of three regions, the pars distalis, pars tuberalis, and pars intermedia. </p> <h3>Pars distalis</h3> <p>The pars distalis (distal part) comprises the majority of the anterior pituitary and is where the bulk of pituitary hormone production occurs. The pars distalis contains two types of cells, including <a href="/facts/Chromophobe_cell/mapxncb5">chromophobe cells</a> and <a href="/facts/Chromophil/KpRIHUDM">chromophil cells</a>.<a class="footnote-ref" id="fnref:1" href="#fn:1"><sup>1</sup></a> The chromophils can be further divided into <a href="/facts/Acidophils/CKNamYEU">acidophils</a> (alpha cells) and <a href="/facts/Basophil_cell/hEv7HVy7">basophils</a> (beta cells).<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> These cells all together produce hormones of the anterior pituitary and release them into the blood stream. </p><p>Nota bene: The terms "basophil" and "acidophil" are used by some books, whereas others prefer not to use these terms. This is due to the possible confusion with white blood cells, where one may also find basophils and acidophils. </p> <h3>Pars tuberalis</h3> <p>The pars tuberalis (tubular part) forms a part of a highly vascularised sheath extending up from the pars distalis, which joins with the <a href="/facts/Pituitary_stalk/eVTWyoKI">pituitary stalk</a> (also known as the infundibular stalk or infundibulum), arising from the posterior lobe. (The pituitary stalk connects the hypothalamus to the posterior pituitary.) The function of the pars tuberalis is poorly understood. However, it has been seen to be important in receiving the endocrine signal in the form of <a href="/facts/TSHB/v31qHkwK">TSHB</a> (a β subunit of TSH), informing the pars tuberalis of the <a href="/facts/Photoperiod/aMpEzjkb">photoperiod</a> (length of day). The expression of this subunit is regulated by the secretion of <a href="/facts/Melatonin/LEyEWg18">melatonin</a> in response to light information transmitted to the <a href="/facts/Pineal_gland/eN9EBq5Q">pineal gland</a>.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a><a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> Earlier studies have shown localization of melatonin receptors in this region.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> </p><p>Principal cells of the pars tuberalis are low columnar in form, with the cytoplasm containing numerous lipid droplets, glycogen granules, and occasional colloid droplets. A sparse population of functional gonadotrophs are present (indicated by immunoreactivity for <a href="/facts/ACTH/o5UBWfGD">ACTH</a>, <a href="/facts/Follicle-stimulating_hormone/n6CwdebD">FSH</a>, and <a href="/facts/Lutenizing_Hormone/a6znte2S">LH</a>).<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> </p> <h3>Pars intermedia</h3> <p>The <a href="/facts/Pars_intermedia/J40XP6Em">pars intermedia</a> (intermediate part) sits between the pars distalis and the posterior pituitary, forming the boundary between the anterior and posterior pituitaries. It is very small and indistinct in humans. </p> <h3>Development</h3> <p>The anterior pituitary is derived from the <a href="/facts/Ectoderm/lg5p0jTL">ectoderm</a>, more specifically from that of <a href="/facts/Rathke%2527s_pouch/fLEDsVA9">Rathke's pouch</a>, part of the developing <a href="/facts/Hard_palate/UKtwNlup">hard palate</a> in the embryo. Rathke's pouch is also <a href="/facts/Ectodermal/lg5p0jTL">ectodermal</a> in origin. </p><p>The pouch eventually loses its connection with the <a href="/facts/Pharynx/51F3eVms">pharynx</a>, giving rise to the anterior pituitary. The anterior wall of Rathke's pouch proliferates, filling most of the pouch to form the pars distalis and the pars tuberalis. The posterior wall of the anterior pituitary forms the pars intermedia. Its formation from the soft tissues of the upper palate contrasts with the posterior pituitary, which originates from <a href="/facts/Neuroectoderm/DU6oF95q">neuroectoderm</a>.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> </p> <h2 id="function">Function</h2> <p>The anterior pituitary contains five types of endocrine cell, and they are defined by the hormones they secrete: <a href="/facts/Somatotropic_cell/05Vx6XyG">somatotropes</a> (GH); <a href="/facts/Prolactin_cell/kjNKITxL">lactotropes</a> (PRL); <a href="/facts/Gonadotropic_cell/bL1H0gs5">gonadotropes</a> (LH and FSH); <a href="/facts/Corticotropic_cell/w2j3wFCt">corticotropes</a> (ACTH) and <a href="/facts/Thyrotropic_cell/0GshhF0L">thyrotropes</a> (TSH).<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> It also contains non-endocrine <a href="/facts/Folliculostellate_cell/UQd1Br0u">folliculostellate cells</a> which are thought to stimulate and support the endocrine cell populations. </p><p>Hormones secreted by the anterior pituitary are <a href="/facts/Trophic_hormone/x7y2RyIf">trophic hormones</a> (Greek: trophe, "nourishment"). Trophic hormones directly affect growth either as hyperplasia or hypertrophy on the tissue it is stimulating. <a href="/facts/Tropic_hormone/KY47Fnkc">Tropic hormones</a> are named for their ability to act directly on target tissues or other <a href="/facts/Endocrine_gland/J6w67lns">endocrine glands</a> to release hormones, causing numerous cascading physiological responses.<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> </p> <table><tbody><tr><th>Hormone</th><th>Other names</th><th>Symbol(s)</th><th>Structure</th><th>Secretory cells</th><th>Staining</th><th>Target</th><th>Effect</th></tr><tr><td><a href="/facts/Adrenocorticotropic_hormone/o5UBWfGD">Adrenocorticotropic hormone</a></td><td>Corticotropin</td><td>ACTH</td><td><a href="/facts/Polypeptide/C4ltc7UG">Polypeptide</a></td><td><a href="/facts/Corticotrophs/w2j3wFCt">Corticotrophs</a></td><td><a href="/facts/Anterior_pituitary_basophil/hEv7HVy7">Basophil</a></td><td><a href="/facts/Adrenal_gland/3f8jV5aJ">Adrenal gland</a></td><td>Secretion of <a href="/facts/Glucocorticoid/2P91Aj3S">glucocorticoid</a>, <a href="/facts/Mineralocorticoid/Ruj1B1Mv">mineralocorticoid</a> and <a href="/facts/Androgen/Rxey0HxX">androgens</a></td></tr><tr><td><a href="/facts/Thyroid-stimulating_hormone/w8ettSpY">Thyroid-stimulating hormone</a></td><td>Thyrotropin</td><td>TSH</td><td><a href="/facts/Glycoprotein/bKPzzW7m">Glycoprotein</a></td><td><a href="/facts/Thyrotrophs/0GshhF0L">Thyrotrophs</a></td><td><a href="/facts/Anterior_pituitary_basophil/hEv7HVy7">Basophil</a></td><td><a href="/facts/Thyroid_gland/bjovTJVu">Thyroid gland</a></td><td>Secretion of <a href="/facts/Thyroid_hormone/9k4xJtCq">thyroid hormones</a></td></tr><tr><td><a href="/facts/Follicle-stimulating_hormone/n6CwdebD">Follicle-stimulating hormone</a></td><td>-</td><td>FSH</td><td>Glycoprotein</td><td><a href="/facts/Gonadotroph/bL1H0gs5">Gonadotrophs</a></td><td><a href="/facts/Anterior_pituitary_basophil/hEv7HVy7">Basophil</a></td><td><a href="/facts/Gonads/36BUam2x">Gonads</a></td><td>Growth of <a href="/facts/Reproductive_system/gL90a4cf">reproductive system</a></td></tr><tr><td><a href="/facts/Luteinizing_hormone/a6znte2S">Luteinizing hormone</a></td><td>Lutropin</td><td>LH, ICSH</td><td>Glycoprotein</td><td><a href="/facts/Gonadotroph/bL1H0gs5">Gonadotrophs</a></td><td><a href="/facts/Anterior_pituitary_basophil/hEv7HVy7">Basophil</a></td><td><a href="/facts/Gonads/36BUam2x">Gonads</a></td><td><a href="/facts/Sex_hormone/mI6bkHII">Sex hormone</a> production</td></tr><tr><td><a href="/facts/Growth_hormone/SLEJ1fws">Growth hormone</a></td><td>Somatotropin</td><td>GH, STH</td><td>Polypeptide</td><td><a href="/facts/Somatotrophs/05Vx6XyG">Somatotrophs</a></td><td><a href="/facts/Acidophil/CKNamYEU">Acidophil</a></td><td><a href="/facts/Liver/Rtp4Fk2b">Liver</a>, <a href="/facts/Adipose_tissue/PxxedB6e">adipose tissue</a></td><td>Promotes growth; <a href="/facts/Lipid/TdQR87HX">lipid</a> and <a href="/facts/Carbohydrate_metabolism/h2WvuF14">carbohydrate metabolism</a></td></tr><tr><td><a href="/facts/Prolactin/NcdqrzFU">Prolactin</a></td><td>Lactotropin</td><td>PRL</td><td>Polypeptide</td><td><a href="/facts/Lactotroph/kjNKITxL">Lactotrophs</a></td><td><a href="/facts/Acidophil/CKNamYEU">Acidophil</a></td><td><a href="/facts/Ovary/z2hG6bNy">Ovaries</a>, <a href="/facts/Mammary_gland/6fVBnNSA">mammary glands</a>, <a href="/facts/Testes/Doy40hoq">testes</a>, <a href="/facts/Prostate/mrBdSsf7">prostate</a></td><td>Secretion of <a href="/facts/Estrogen/dPEewnDV">estrogens</a>/<a href="/facts/Progesterone/WEj2TGRm">progesterone</a>; <a href="/facts/Lactation/0w1HoW27">lactation</a>; <a href="/facts/Spermatogenesis/8u8XNEV6">spermatogenesis</a>; <a href="/facts/Prostatic_hyperplasia/ocGSCVK9">prostatic hyperplasia</a></td><td><a href="/facts/Thyroid-stimulating_hormone/w8ettSpY">TSH</a> and <a href="/facts/ACTH/o5UBWfGD">ACTH</a> secretion</td></tr></tbody></table> <p><a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a><a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a> </p> <h3>Role in the endocrine system</h3> <p class="note">Main article: <a href="/facts/Hypothalamus/lCkNt1bM">Hypothalamus</a></p> <h3>Hypothalamic control</h3> <p>Hormone secretion from the anterior pituitary gland is regulated by hormones secreted by the <a href="/facts/Hypothalamus/lCkNt1bM">hypothalamus</a>. <a href="/facts/Neuroendocrine_cells/7GVp7Gn9">Neuroendocrine cells</a> in the hypothalamus project <a href="/facts/Axons/5DCd4wLo">axons</a> to the <a href="/facts/Median_eminence/99rzqoG8">median eminence</a>, at the base of the brain. At this site, these cells can release substances into small blood vessels that travel directly to the anterior pituitary gland (the <a href="/facts/Hypophyseal_portal_system/gNpabWYT">hypothalamo-hypophyseal portal vessels</a>). </p> <h3>Other mechanisms</h3> <p>Aside from hypothalamic control of the anterior pituitary, other systems in the body have been shown to regulate the anterior pituitary's function. <a href="/facts/GABA/vRTeQQUG">GABA</a> can either stimulate or inhibit the secretion of <a href="/facts/Luteinizing_hormone/a6znte2S">luteinizing hormone</a> (LH) and <a href="/facts/Growth_hormone/SLEJ1fws">growth hormone</a> (GH) and can stimulate the secretion of <a href="/facts/Thyroid-stimulating_hormone/w8ettSpY">thyroid-stimulating hormone</a> (TSH). <a href="/facts/Prostaglandin/kIKw0gDj">Prostaglandins</a> are now known to inhibit <a href="/facts/Adrenocorticotropic_hormone/o5UBWfGD">adrenocorticotropic hormone</a> (ACTH) and also to stimulate TSH, GH and LH release.<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a> Clinical evidence supports the experimental findings of the excitatory and inhibitory effects GABA has on <a href="/facts/Growth_hormone/SLEJ1fws">GH</a> secretion, dependent on GABA's site of action within the hypothalamic-pituitary axis.<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a> </p> <h3>Effects of the anterior pituitary</h3> Thermal homeostasis <p>The homeostatic maintenance of the anterior pituitary is crucial to our physiological well being. Increased plasma levels of <a href="/facts/Thyroid-stimulating_hormone/w8ettSpY">TSH</a> induce <a href="/facts/Hyperthermia/WMHlf9j7">hyperthermia</a> through a mechanism involving increased <a href="/facts/Metabolism/WxDrm8k5">metabolism</a> and <a href="/facts/Cutaneous/4havlLzG">cutaneous</a> <a href="/facts/Vasodilation/cjzrU8Ro">vasodilation</a>. Increased levels of <a href="/facts/Luteinizing_hormone/a6znte2S">LH</a> also result in <a href="/facts/Hypothermia/lIYDCIAv">hypothermia</a> but through a decreased metabolism action. <a href="/facts/ACTH/o5UBWfGD">ACTH</a> increase metabolism and induce cutaneous vasoconstriction, increased plasma levels also result in <a href="/facts/Hyperthermia/WMHlf9j7">hyperthermia</a> and <a href="/facts/Prolactin/NcdqrzFU">prolactin</a> decreases with decreasing temperature values. <a href="/facts/Follicle-stimulating_hormone/n6CwdebD">follicle-stimulating hormone</a> (FSH) also may cause <a href="/facts/Hypothermia/lIYDCIAv">hypothermia</a> if increased beyond homeostatic levels through an increased metabolic mechanism only.<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a> </p> Gonadal function <p><a href="/facts/Gonadotrope/bL1H0gs5">Gonadotropes</a>, primarily <a href="/facts/Luteinising_hormone/a6znte2S">luteinising hormone</a> (LH) secreted from the anterior pituitary stimulates the <a href="/facts/Ovulation_cycle/AY6Y9xxM">ovulation cycle</a> in female <a href="/facts/Mammal/phSwTzBo">mammals</a>, whilst in the males, LH stimulates the synthesis of <a href="/facts/Androgen/Rxey0HxX">androgen</a> which drives the ongoing will to mate together with a constant production of <a href="/facts/Sperm/RCxpXygQ">sperm</a>.<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a> </p> HPA axis <p>Main article <i><a href="/facts/Hypothalamic-pituitary-adrenal_axis/062CevaI">Hypothalamic-pituitary-adrenal axis</a></i> </p><p>The anterior pituitary plays a role in stress response. <a href="/facts/Corticotropin_releasing_hormone/3TK6s0gP">Corticotropin releasing hormone</a> (CRH) from the hypothalamus stimulates <a href="/facts/ACTH/o5UBWfGD">ACTH</a> release in a cascading effect that ends with the production of glucocorticoids from the <a href="/facts/Adrenal_cortex/t4EkJgdy">adrenal cortex</a>.<a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a> </p> <h3>Behavioral effects</h3> Development The release of GH, LH, and FSH are required for correct human development, including gonadal development.<a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a> Breast-feeding Release of the hormone <a href="/facts/Prolactin/NcdqrzFU">prolactin</a> is essential for <a href="/facts/Lactation/0w1HoW27">lactation</a>.<a class="footnote-ref" id="fnref:18" href="#fn:18"><sup>18</sup></a> Stress Operating through the <a href="/facts/Hypothalamic-pituitary-adrenal_axis/062CevaI">hypothalamic-pituitary-adrenal axis</a> (HPA), the anterior pituitary gland has a large role in the <a href="/facts/Neuroendocrine_system/lVldJ7MB">neuroendocrine system</a>'s stress response. Stress induces a release of <a href="/facts/Corticotropin-releasing_hormone/3TK6s0gP">corticotropin-releasing hormone</a> (CRH) and <a href="/facts/Vasopressin/B1EksWWY">vasopressin</a> from the <a href="/facts/Hypothalamus/lCkNt1bM">hypothalamus</a>, which activates the release of <a href="/facts/Adrenocorticotropic_hormone/o5UBWfGD">adrenocorticotropic hormone</a> (ACTH) from the anterior pituitary gland. Then, this acts on the <a href="/facts/Adrenal_cortex/t4EkJgdy">adrenal cortex</a> to produce <a href="/facts/Glucocorticoids/2P91Aj3S">glucocorticoids</a> such as <a href="/facts/Cortisol/5IvRV0cm">cortisol</a>. These <a href="/facts/Glucocorticoids/2P91Aj3S">glucocorticoids</a> act back on the anterior pituitary gland and the <a href="/facts/Hypothalamus/lCkNt1bM">hypothalamus</a> with <a href="/facts/Negative_feedback/G9byVgpN">negative feedback</a> to slow the production of CRH and ACTH.<a class="footnote-ref" id="fnref:19" href="#fn:19"><sup>19</sup></a><a class="footnote-ref" id="fnref:20" href="#fn:20"><sup>20</sup></a> Increased <a href="/facts/Cortisol/5IvRV0cm">cortisol</a> under stress conditions can cause the following: metabolic effects (mobilization of <a href="/facts/Glucose/oUSkoLCD">glucose</a>, fatty acids, and <a href="/facts/Amino_acids/WDxYwBny">amino acids</a>), bone re-absorption (calcium mobilization), activation of the <a href="/facts/Sympathetic_nervous_system/hs8psNRd">sympathetic nervous system</a> response (fight or flight), anti-inflammatory effects, and inhibition of reproduction/growth.<a class="footnote-ref" id="fnref:21" href="#fn:21"><sup>21</sup></a> When the anterior pituitary gland is removed (<a href="/facts/Hypophysectomy/eq6aVQXW">hypophysectomy</a>) in rats, their <a href="/facts/Avoidance_learning/Vd6KMcgm">avoidance learning</a> mechanisms were slowed, but injections of ACTH restored their performance.<a class="footnote-ref" id="fnref:22" href="#fn:22"><sup>22</sup></a> In addition, stress may delay the release of reproductive hormones such as <a href="/facts/Luteinizing_hormone/a6znte2S">luteinizing hormone</a> (LH) and <a href="/facts/Follicle-stimulating_hormone/n6CwdebD">follicle-stimulating hormone</a> (FSH).<a class="footnote-ref" id="fnref:23" href="#fn:23"><sup>23</sup></a> This shows that the anterior pituitary gland is involved in behavioral functions as well as being part of a larger pathway for stress responses. It is also known that (HPA) hormones are related to certain skin diseases and skin homeostasis. There is evidence linking hyperactivity of HPA hormones to stress-related skin diseases and skin tumors.<a class="footnote-ref" id="fnref:24" href="#fn:24"><sup>24</sup></a> Aging Operating through the <a href="/facts/Hypothalamic-pituitary-gonadal_axis/0G9ALlpQ">hypothalamic-pituitary-gonadal axis</a>, the anterior pituitary gland also affects the <a href="/facts/Reproductive_system/gL90a4cf">reproductive system</a>. The hypothalamus releases <a href="/facts/Gonadotropin-releasing_hormone/hSsFPpdj">gonadotropin-releasing hormone</a> (GnRH), which stimulates the release of <a href="/facts/Luteinizing_hormone/a6znte2S">luteinizing hormone</a> (LH) and <a href="/facts/Follicle-stimulating_hormone/n6CwdebD">follicle-stimulating hormone</a>. Then the <a href="/facts/Gonads/36BUam2x">gonads</a> produce <a href="/facts/Estrogen/dPEewnDV">estrogen</a> and <a href="/facts/Testosterone/uUumdhAz">testosterone</a>. The decrease in release of <a href="/facts/Gonadotropin/Jo53mSXC">gonadotropins</a> (LH and FSH) caused by normal aging may be responsible for <a href="/facts/Impotence/7HDetsos">impotence</a><a class="footnote-ref" id="fnref:25" href="#fn:25"><sup>25</sup></a><a class="footnote-ref" id="fnref:26" href="#fn:26"><sup>26</sup></a> and <a href="/facts/Frailty_syndrome/T1Mho2tf">frailty</a><a class="footnote-ref" id="fnref:27" href="#fn:27"><sup>27</sup></a> in elderly men because of the eventual decrease in production of testosterone. This lower level of <a href="/facts/Testosterone/uUumdhAz">testosterone</a> can have other effects, such as reduced <a href="/facts/Libido/g1Eb72tA">libido</a>, well-being and mood, muscle and bone strength, and metabolism.<a class="footnote-ref" id="fnref:28" href="#fn:28"><sup>28</sup></a> Tactile responding It has been shown that infant mice who were stroked with a paintbrush (simulating motherly care) had more release and binding of <a href="/facts/Growth_hormone/SLEJ1fws">growth hormone</a> (GH) from the anterior pituitary gland.<a class="footnote-ref" id="fnref:29" href="#fn:29"><sup>29</sup></a> Circadian rhythms Light information received by the eyes is transmitted to the <a href="/facts/Pineal_gland/eN9EBq5Q">pineal gland</a> via the <a href="/facts/Circadian_clock/ckgjf1h5">circadian pacemaker</a> (the <a href="/facts/Suprachiasmatic_nucleus/SILs86zl">suprachiasmatic nucleus</a>). Diminishing light stimulates the release of <a href="/facts/Melatonin/LEyEWg18">melatonin</a> from the pineal gland which can also affect the secretion levels in the <a href="/facts/Hypothalamic-pituitary-gonadal_axis/0G9ALlpQ">hypothalamic-pituitary-gonadal axis</a>.<a class="footnote-ref" id="fnref:30" href="#fn:30"><sup>30</sup></a> Melatonin can lower levels of LH and FSH, which will decrease levels of <a href="/facts/Estrogen/dPEewnDV">estrogen</a> and testosterone. In addition, melatonin may affect production of <a href="/facts/Prolactin/NcdqrzFU">prolactin</a>.<a class="footnote-ref" id="fnref:31" href="#fn:31"><sup>31</sup></a> <h2 id="clinical-significance">Clinical significance</h2> <h3>Increased activity</h3> <p class="note">Main article: <a href="/facts/Hyperpituitarism/gTWvS1jV">Hyperpituitarism</a></p> <p><a href="/facts/Hyperpituitarism/gTWvS1jV">Hyperpituitarism</a> is the condition where the pituitary secretes excessive amounts of hormones. This hypersecretion often results in the formation of a <a href="/facts/Pituitary_adenoma/43YK6qa0">pituitary adenoma</a> (tumour), which are benign apart from a tiny fraction. There are mainly three types of anterior pituitary tumors and their associated disorders. For example, <a href="/facts/Acromegaly/caqcbMmM">acromegaly</a> results from excessive secretion of growth hormone (GH) often being released by a pituitary adenoma. This disorder can cause disfigurement and possibly death<a class="footnote-ref" id="fnref:32" href="#fn:32"><sup>32</sup></a> and can lead to <a href="/facts/Gigantism/SPCXXl58">gigantism</a>, a hormone disorder shown in "giants" such as <a href="/facts/Andr%25C3%25A9_the_Giant/tQ64oqY6">André the Giant</a>, where it occurs before the <a href="/facts/Epiphyseal_plates/Q1VuGTDS">epiphyseal plates</a> in bones close in puberty.<a class="footnote-ref" id="fnref:33" href="#fn:33"><sup>33</sup></a> The most common type of pituitary tumour is a <a href="/facts/Prolactinoma/Tx212XNU">prolactinoma</a> which hypersecretes <a href="/facts/Prolactin/NcdqrzFU">prolactin</a>.<a class="footnote-ref" id="fnref:34" href="#fn:34"><sup>34</sup></a> A third type of pituitary adenoma secretes excess ACTH, which in turn, causes an excess of <a href="/facts/Cortisol/5IvRV0cm">cortisol</a> to be secreted and is the cause of <a href="/facts/Cushing%2527s_disease/HqfLkI5J">Cushing's disease</a>.<a class="footnote-ref" id="fnref:35" href="#fn:35"><sup>35</sup></a> </p> <h3>Decreased activity</h3> <p class="note">Main article: <a href="/facts/Hypopituitarism/BavBhRkA">Hypopituitarism</a></p> <p><a href="/facts/Hypopituitarism/BavBhRkA">Hypopituitarism</a> is characterized by a decreased secretion of hormones released by the anterior pituitary. For example, hypo-secretion of GH prior to puberty can be a cause of <a href="/facts/Dwarfism/3dLeF5gt">dwarfism</a>. In addition, <a href="/facts/Addison%2527s_Disease/Lp8AqjEX">secondary adrenal insufficiency</a> can be caused by hypo-secretion of ACTH which, in turn, does not signal the adrenal cortex to produce a sufficient amount of <a href="/facts/Cortisol/5IvRV0cm">cortisol</a>. This is a life-threatening condition. <a href="/facts/Hypopituitarism/BavBhRkA">Hypopituitarism</a> could be caused by the destruction or removal of the anterior pituitary tissue through traumatic brain injury, tumor, <a href="/facts/Tuberculosis/ggPyovAl">tuberculosis</a>, or <a href="/facts/Syphilis/fdnGLyLT">syphilis</a>, among other causes. This disorder used to be referred to as <a href="/facts/Simmonds%2527_disease/VKEzfJ6h">Simmonds' disease</a> but now according to the <a href="/facts/Diseases_Database/pe46JdN2">Diseases Database</a> it is called <a href="/facts/Sheehan_syndrome/VKEzfJ6h">Sheehan syndrome</a>.<a class="footnote-ref" id="fnref:36" href="#fn:36"><sup>36</sup></a> If the hypopituitarism is caused by the blood loss associated with childbirth, the disorder is referred to as Sheehan syndrome. </p> <h2 id="history">History</h2> <h3>Etymology</h3> <p>The anterior pituitary is also known as the adenohypophysis, meaning "glandular undergrowth", from the <a href="/facts/Ancient_Greek/LIK7NlUh">Greek</a> <i>adeno-</i> ("gland"), <i>hypo</i> ("under"), and <i>physis</i> ("growth"). </p> <h2 id="additional-images">Additional images</h2> <h2 id="see-also">See also</h2> <p class="note">This article uses <a href="/facts/Anatomical_terminology/n3IASQlr">anatomical terminology</a>.</p> <ul><li><a href="/facts/Triple_bolus_test/sznnzRLh">Triple bolus test</a></li> <li><a href="/facts/Hypothalamic%25E2%2580%2593pituitary%25E2%2580%2593somatic_axis/0GoSBl18">Hypothalamic–pituitary–somatic axis</a></li></ul> <h2 id="further-reading">Further reading</h2> <ul><li>Marieb, E. 2004. Human Anatomy and Physiology. Benjamin Cummings: New York.</li> <li>Wheater, P., Burkitt, H., Daniels, V. 1987. Functional Histology. Churchill Livingstone: New York.</li></ul> <h2 id="external-links">External links</h2> <ul><li><a href="https://www.bu.edu/phpbin/medlib/histology/p/14002loa.htm">Histology image: 14002loa</a> – Histology Learning System at Boston University</li> <li><a href="http://www.med.unc.edu/embryo_images/unit-nervous/nerv_htms/nerv016a.htm">Embryology at unc.edu</a></li> <li><a href="http://www.pituitary.org">The Pituitary Network Association -- www.pituitary.org</a></li> <li><a href="http://www.websparrow.org/pharmacy/secretion-of-hormones-from-the-anterior-pituitary-gland">Secretion of hormones from the Anterior Pituitary Gland</a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Eroschenko, Victor P.; Fiore, Mariano S. H. di (2013-01-01). DiFiore's Atlas of Histology with Functional Correlations. Lippincott Williams & Wilkins. 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