Posterior pituitary
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2008-06-23T15:50:31Z
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robot Modifying: [[de:Neurohypophyse]]
{{Infobox Anatomy |
Name = {{PAGENAME}} |
Latin = |
GraySubject = 275 |
GrayPage = 1275 |
Image = Pituitary gland.PNG |
Caption = Pituitary gland. Posterior pituitary is in blue. Pars nervosa and infundibular stalk are not labeled, but pars nervosa is at bottom and infundibular stalk is at top.) |
Image2 = Gray1181.png |
Caption2 = Median sagittal through the hypophysis of an adult monkey. (Posterior lobe labeled at bottom right.) |
Precursor = [[Neural tube]] (downward-growth of the [[diencephalon]])<ref>[http://www.med.unc.edu/embryo_images/unit-nervous/nerv_htms/nerv016a.htm Embryology at unc.edu]</ref> |
System = |
Artery = [[inferior hypophyseal artery]] |
Vein = [[hypophyseal vein]] |
Nerve = |
Lymph = |
MeshName = Pituitary+Gland,+Posterior |
MeshNumber = A06.407.747.734 |
DorlandsPre = n_07 |
DorlandsSuf = 12569241 |
}}
The '''posterior pituitary''' (or '''neurohypophysis''') comprises the [[posterior]] lobe of the [[pituitary gland]] and is part of the [[endocrine system]].
==Anatomy==
The '''Posterior Pituitary Gland''' consists mainly of [[neuron]]al projections ([[axon]]s) extending from the [[supraoptic nucleus|supraoptic]] and [[paraventricular nucleus|paraventricular nuclei]] of the [[hypothalamus]] that secrete [[peptide hormone]]s into the capillaries of the [[hypophyseal circulation]].
The neurohypophysis also contains a specialised type of [[astrocytic]] [[glial cell]] - "[[pituicytes]]".
Despite its name, the posterior pituitary gland is not a gland, ''per se''; rather, it is largely a collection of [[axon]]al projections from the hypothalamus that terminate behind the [[anterior pituitary gland]].
Classification of the posterior pituitary varies, but most sources include the three regions below:
{| class="wikitable"
| '''Region''' || '''Description'''
|-
| pars nervosa, or neural lobe, or posterior lobe<ref>{{Dorlands|l_13|12501193}}</ref> || This region consistutes the majority of the posterior pituitary, and is sometimes (incorrectly) considered synonymous with it. Notable features include [[Herring bodies]] and [[pituicytes]]. <ref>{{BUHistology|14004loa}}</ref>
|-
| [[infundibular stalk]] || Also known as the "infundibulum" or "pituitary stalk". The term "hypothalamic-hypophyseal tract" is a near-synonym, describing the connection rather than the structure.
|-
| [[median eminence]] || This is only occasionally included as part of the posterior pituitary.<ref>{{Dorlands|n_07|12569241}}</ref> Other sources specifically exclude it from the pituitary.<ref>{{MeshName|Median+eminence}}</ref>
|}
A few sources include the [[pars intermedia]] as part of the posterior lobe, but this is a minority view. It is based upon the gross anatomical separation of the posterior and anterior pituitary along the cystic remnants of Rathke's pouch, causing the pars intermedia to remain attached to the neurohypophysis.
==Major hormones secreted==
Hormones known classically as posterior pituitary hormones are synthesized by the hypothalamus. They are then stored and secreted by the posterior pituitary into the bloodstream.
{| class="wikitable"
! Hormone
! Other names
! Symbol(s)
! Target
! Effect
! Source
|-
| [[Oxytocin]]
| -
| -
| [[Uterus]], [[mammary gland]]s
| [[Uterine contraction]]s; [[lactation]]
| [[supraoptic nucleus|supraoptic]] and [[paraventricular nucleus|paraventricular nuclei]]
|-
| [[Vasopressin]]
| Arginine vasopressin, argipressin, antidiuretic hormone
| AVP, ADH
| [[Kidney]]s or [[Arteriole]]s
| Stimulates water retention; raises blood pressure by contracting arterioles, induces male aggression
| [[supraoptic nucleus|supraoptic]] and [[paraventricular nucleus|paraventricular nuclei]]
|}
==Role in disease==
''Insufficient secretion'' of [[vasopressin]] is central to[[diabetes insipidus| diabetes insipidus]], in which the body loses the capacity to concentrate urine. Affected individuals excrete as much as 20 L of dilute urine per day.
''Oversecretion'' of vasopressin causes the [[syndrome of inappropriate antidiuretic hormone]].
==References==
<references/>
==Additional images==
<gallery><gallery>
Image:Gray1180.png|The posterior pituitary comprises the posterior lobe of the pituitary gland.
Image:Nasennebenhöhlen.gif
Image:HypothalamicNuclei.PNG|Hypothalamic nuclei
</gallery>
==See Also==
[[anterior pituitary]]
{{pituitary gland}}
{{Diencephalon}}
[[Category:Endocrine system]]
[[Category:Neuroendocrinology]]
[[de:Neurohypophyse]]
[[es:Neurohipófisis]]
[[fr:Neurohypophyse]]
[[sq:Hormonet e pjesës së prapme të hipofizës]]
[[fi:Neurohypofyysi]]