Posterior pituitary

Source: Wikipedia, the free encyclopedia.
Posterior pituitary
inferior hypophyseal artery
Veinhypophyseal vein
Identifiers
Latinpars nervosa glandulae pituitariae,
pars nervosa hypophyseos,
lobus posterior hypophyseos
MeSHD010904
NeuroNames401
NeuroLex IDbirnlex_1586
TA98A11.1.00.006
TA23859
FMA74636
Anatomical terminology]

The posterior pituitary (or neurohypophysis) is the

paraventricular nucleus and supraoptic nucleus), posterior pituitary, and these axonal projections.[2]

Structure

The posterior pituitary consists mainly of

glial cells resembling astrocytes assisting in the storage and release of the hormones.[3]

Classification of the posterior pituitary varies, but most sources include the two regions below:

Pars nervosa

Also called the neural lobe or posterior lobe, this region constitutes the majority of the posterior pituitary and is the storage site of oxytocin and vasopressin. Sometimes (incorrectly) considered synonymous with the posterior pituitary, the pars nervosa includes Herring bodies and pituicytes.[4]

Infundibular stalk

Main article: Pituitary stalk

Also known as the infundibulum or pituitary stalk, the infundibular stalk bridges the hypothalamic and hypophyseal systems.

The median eminence is only occasionally included as part of the posterior pituitary. Other sources specifically exclude it from the pituitary.[5]

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.

Function

Hormone secretion

Two hormones are classically considered as being related to the posterior pituitary: oxytocin and vasopressin. These hormones are created in the hypothalamus and released in the posterior pituitary. After creation, they are stored in neurosecretory vesicles regrouped into Herring bodies before being secreted in the posterior pituitary via the bloodstream.

Hormone Other names Symbol(s) Main targets Effect Source
Oxytocin OT, OXY Uterus, mammary glands Uterine contractions; lactation
paraventricular nuclei
Vasopressin Arginine vasopressin, antidiuretic hormone VP, AVP, ADH Kidneys and arterioles Stimulates water retention; raises blood pressure by contracting arterioles
paraventricular nuclei

Clinical significance

Insufficient secretion of

syndrome of inappropriate antidiuretic hormone
(SIADH).

See also

This article uses anatomical terminology.

References

  1. ^ Embryology at unc.edu
  2. ^
    ISBN 9780071481274
    .
    •The hypothalamic–neurohypophyseal system secretes two peptide hormones directly into the blood, vasopressin and oxytocin. ...
    •The hypothalamic–pituitary–adrenal (HPA) axis. It comprises corticotropin-releasing factor (CRF), released by the hypothalamus; adrenocorticotropic hormone (ACTH), released by the anterior pituitary; and glucocorticoids, released by the adrenal cortex.
    •The hypothalamic–pituitary–thyroid axis consists of hypothalamic thyrotropin-releasing hormone (TRH); the anterior pituitary hormone thyroid–stimulating hormone (TSH); and the thyroid hormones T3 and T4.
    •The hypothalamic–pituitary–gonadal axis comprises hypothalamic gonadotropin–releasing hormone (GnRH), the anterior pituitary luteinizing hormone (LH) and follicle-stimulating hormone (FSH), and the gonadal steroids.
  3. PMID 3062122
    .
  4. ISBN 978-0195151732
    .
  5. ^ Median+eminence at the U.S. National Library of Medicine Medical Subject Headings (MeSH)

Additional images

  • The posterior pituitary comprises the posterior lobe of the pituitary gland.
    The posterior pituitary comprises the posterior lobe of the pituitary gland.

External links

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