Editing Pituitary gland (section)

== Structure ==
In humans, the pituitary gland rests upon the [[hypophyseal fossa]] of the [[sphenoid bone]], in the center of the [[middle cranial fossa]]. It sits in a protective bony enclosure called the [[sella turcica]], covered by a fold of [[dura mater]] known as the  [[diaphragma sellae]].<ref>{{cite book |title=Gray's Clinical Anatomy |publisher=Elsevier Health Sciences |year=2011 |isbn=978-1-4377-3580-2 |editor-last=Mancall |editor-first=Elliott L. |page=154 |chapter=Cranial Fossae |editor-last2=Brock |editor-first2=David G. |chapter-url=https://books.google.com/books?id=R6ARC5tdhtYC&pg=PA154}}</ref> 

The pituitary gland is composed of the [[anterior pituitary]], the [[posterior pituitary]], and an [[pars intermedia|intermediate lobe]] that joins them.<ref>{{cite journal |vauthors=Ganapathy MK, Tadi P | title = Anatomy, Head and Neck, Pituitary Gland |journal=StatPearls [Internet] | publisher = StatPearls Publishing | date = Jan 2020 | pmid = 31855373 | url = https://www.ncbi.nlm.nih.gov/books/NBK551529/ | access-date = 24 Sep 2020}}</ref> The intermediate lobe is [[avascular]] and almost absent in humans, but  in many other animals, it is distinct. The intermediate lobe in rats and mice have been extensively studied for the development of the pituitary and its functions.<ref name=":0">{{Cite book|title = The Pituitary -|url = https://archive.org/details/pituitaryrdediti00melm|url-access = limited|last = Melmed|first = Shlomo|publisher = Academic Press is an imprint of Elsevier|year = 2011|isbn = 978-0-12-380926-1|location = San Diego, CA |pages = [https://archive.org/details/pituitaryrdediti00melm/page/n25 23]–25|edition = Third}}{{deadlink|date=April 2025}}</ref> In all animals, the fleshy, glandular anterior pituitary is distinct from the neural composition of the posterior pituitary, which is an extension of the [[hypothalamus]].<ref name=":0" />

The height of the pituitary gland ranges from 5.3 to 7.0 mm. The volume of the pituitary gland ranges from 200 to 440&nbsp;mm<sup>3</sup>.<ref name=":1">{{Cite journal |last1=Yadav |first1=Pratiksha |last2=Singhal |first2=Shubham |last3=Chauhan |first3=Surbhi |last4=Harit |first4=Saumya |date=2017 |title=MRI Evaluation of Size and Shape of Normal Pituitary Gland: Age and Sex Related Changes |journal=Journal of Clinical and Diagnostic Research |url=http://jcdr.net/article_fulltext.asp?issn=0973-709x&year=2017&volume=11&issue=12&page=TC01&issn=0973-709x&id=10933 |doi=10.7860/JCDR/2017/31034.10933|doi-access=free }}</ref> Its most common shape, found in 46% of people is flat, it is convex in 31.2% and concave in 22.8%.<ref name=":1" />

=== Anterior ===
{{Main|Anterior pituitary}}
The anterior pituitary lobe (adenohypophysis) arises from an [[evagination]] of the oral [[ectoderm]] ([[Rathke's pouch]]). This contrasts with the [[posterior pituitary]], which originates from [[neuroectoderm]].

[[Endocrine cell]]s of the anterior pituitary are controlled by regulatory hormones released by [[parvocellular neurosecretory cell]]s in the hypothalamic capillaries leading to infundibular blood vessels, which in turn lead to a second capillary bed in the anterior pituitary. This vascular relationship constitutes the [[hypophyseal portal system]]. Diffusing out of the second capillary bed, the hypothalamic [[releasing hormone]]s then bind to anterior pituitary endocrine cells, upregulating or downregulating their release of hormones.<ref name="Boron2009">{{cite book | last1=Boron | first1=Walter F. | last2=Boulpaep | first2=Emile L. | title=Medical Physiology | edition=2nd | publisher=Saunders Elsevier | location=Philadelphia | year=2009 | isbn=978-1-4160-3115-4 | pages=1016–1017}}</ref>

The anterior lobe of the pituitary can be divided into the [[pars tuberalis]] (pars infundibularis) and [[pars distalis]] (pars glandularis) that constitutes ~80% of the gland. The [[pars intermedia]] (the intermediate lobe) lies between the pars distalis and the pars tuberalis, and is rudimentary in the human, although in other species it is more developed.<ref name=":0" /> It develops from a depression in the dorsal wall of the [[pharynx]] (stomal part) known as Rathke's pouch.

The [[anterior pituitary]] contains several different types of cells that synthesize and secrete hormones.<ref>{{Cite book|title=Textbook of Medical Physiology|publisher=Elsevier Saunders}}</ref> Usually there is one type of cell for each major hormone formed in the anterior pituitary. At least five different cell types can be differentiated using various [[Staining|stain]]s.

{| class="wikitable"
! Hormone
! Other names
! Symbol(s)
! Structure
! Secretory cells
! Staining
! Target
! Effect
|-
| [[Adrenocorticotropic hormone]]
| Corticotropin
| ACTH
| [[Polypeptide]]
| [[Corticotrophs]]
| [[Anterior pituitary basophil|Basophil]]
| [[Adrenal gland]]
| Secretion of [[glucocorticoid]], [[mineralocorticoid]] and [[androgen]]s
|-
| [[Thyroid-stimulating hormone]]
| Thyrotropin
| TSH
| [[Glycoprotein]]
| [[Thyrotrophs]]
| [[Anterior pituitary basophil|Basophil]]
| [[Thyroid gland]]
| Secretion of [[thyroid hormone]]s
|-
| [[Follicle-stimulating hormone]]
| -
| FSH
| Glycoprotein
| [[Gonadotroph]]s
| [[Anterior pituitary basophil|Basophil]]
| [[Gonads]]
| Growth of [[reproductive system]]
|-
| [[Luteinizing hormone]]
| Lutropin
| LH, ICSH
| Glycoprotein
| [[Gonadotroph]]s
| [[Anterior pituitary basophil|Basophil]]
| [[Gonads]]
| [[Sex hormone]] production
|-
| [[Growth hormone]]
| Somatotropin
| GH, STH
| Polypeptide
| [[Somatotrophs]]
| [[Acidophil]]
| [[Liver]], [[adipose tissue]]
| Promotes growth; [[lipid]] and [[carbohydrate metabolism]]
|-
| [[Prolactin]]
| Lactotropin
| PRL
| Polypeptide
| [[Lactotroph]]s
| [[Acidophil]]
| [[Ovary|Ovaries]], [[mammary gland]]s, [[testes]], [[prostate]]
| Secretion of [[estrogen]]s/[[progesterone]]; [[lactation]]; [[spermatogenesis]]; [[prostatic hyperplasia]]
| [[Thyroid-stimulating hormone|TSH]] and [[ACTH]] secretion
|}
<ref>Malendowicz, L.K; Rucinski, M; Belloni, A.S; Ziolkowska, A; and Nussdorfer, G.C. (2007) Leptin and the regulation of the hypothalamic-pituitary-adrenal axis. Int Rev Cytol. 263: 63-102.</ref><ref>Sone, M. and Osamura, R.Y. (2001) Leptin and the pituitary. Pituitary. Jan-Apr; 4(1-2): 15-23.</ref>

=== Posterior ===
{{Main|Posterior pituitary}}
The [[posterior pituitary]] consists of the posterior lobe and the [[pituitary stalk]] (infundibulum) that connects it to the hypothalamus. It develops as an extension of the hypothalamus, from the floor of the [[third ventricle]]. The posterior pituitary hormones are synthesized by cell bodies in the [[hypothalamus]]. The [[magnocellular neurosecretory cell]]s, of the supraoptic and paraventricular nuclei located in the hypothalamus, project axons down the infundibulum to terminals in the posterior pituitary. This simple arrangement differs sharply from that of the adjacent anterior pituitary, which does not develop from the hypothalamus.

The release of pituitary hormones by both the anterior and posterior lobes is under the control of the [[hypothalamus]], albeit in different ways.<ref name="Boron2009" />