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The pituitary gland or hypophysis is an endocrine gland in . In , the pituitary gland is located at the base of the human brain, protruding off the bottom of the hypothalamus. The pituitary gland and the hypothalamus control much of the body's endocrine system. (2025). 9780073378251, McGraw-Hill. ISBN 9780073378251 It is seated in part of the sella turcica, a depression in the sphenoid bone, known as the hypophyseal fossa. The human pituitary gland is ovoid, about 1 cm in diameter, in weight on average, and about the size of a kidney bean. (2025). 9781416045748, Saunders/Elsevier. ISBN 9781416045748 (2025). 9780702052309, Elsevier. ISBN 9780702052309 Digital version.
There are two main lobes of the pituitary, an anterior lobe, and a posterior lobe joined and separated by a small intermediate lobe. The anterior lobe (adenohypophysis) is the glandular part that produces and secretes several . The posterior lobe (neurohypophysis) secretes neurohypophysial hormones produced in the hypothalamus. Both lobes have different origins and they are both controlled by the hypothalamus.
secreted from the pituitary gland help to control growth, blood pressure, energy management, all functions of the , thyroid gland, metabolism, as well as some aspects of pregnancy, childbirth, breastfeeding, osmoregulation at the , temperature regulation, and pain relief.
The pituitary gland is composed of the anterior pituitary, the posterior pituitary, and an pars intermedia that joins them. 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. 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.
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 mm3. Its most common shape, found in 46% of people is flat, it is convex in 31.2% and concave in 22.8%.
of the anterior pituitary are controlled by regulatory hormones released by parvocellular neurosecretory cells 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 hormones then bind to anterior pituitary endocrine cells, upregulating or downregulating their release of hormones. (2025). 9781416031154, Saunders Elsevier. ISBN 9781416031154
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. 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. 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.
| Adrenocorticotropic hormone | Corticotropin | ACTH | Polypeptide | Corticotrophs | Basophil | Adrenal gland | Secretion of glucocorticoid, mineralocorticoid and | |
| Thyroid-stimulating hormone | Thyrotropin | TSH | Glycoprotein | Thyrotrophs | Basophil | Thyroid gland | Secretion of | |
| Follicle-stimulating hormone | - | FSH | Glycoprotein | Basophil | Gonads | Growth of reproductive system | ||
| Luteinizing hormone | Lutropin | LH, ICSH | Glycoprotein | 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 | Acidophil | Ovary, , testes, prostate | Secretion of /progesterone; lactation; spermatogenesis; prostatic hyperplasia | TSH and ACTH secretion |
The release of pituitary hormones by both the anterior and posterior lobes is under the control of the hypothalamus, albeit in different ways.
Somatotropes:
Corticotropes:
Gonadotropes:
These hormones are released from the anterior pituitary under the influence of the hypothalamus. Hypothalamic hormones are secreted to the anterior lobe by way of a special capillary system, called the hypothalamic-hypophysial portal system.
There is also a non-endocrine cell population called folliculostellate cells.
Magnocellular neurons:
Differentiation and cell migration takes place in weeks 5 and 6. Rathke's pouch grows towards the developing brain. The upper part of the pouch eventually constricts and detaches from the oral cavity, and cells in Rathke's pouch differentiate to form three parts of the adenohypophysis: the pars distalis, pars intermedia, and pars tuberalis.
In weeks 4 to 8 the posterior pituitary is formed. The infundibulum from the diencephalon elongates downward, forming a stalk that connects with Rathke’s pouch. This stalk will develop into the posterior pituitary where specialized cells from the hypothalamus, known as , migrate to help store and release hormones such as oxytocin and vasopressin.
From week 12 to week 16, the anterior pituitary starts to produce hormones, notably growth hormone and around the 12th to 16th week of gestation, the anterior pituitary begins producing hormones like growth hormone (GH), and adrenocorticotropic hormone (ACTH), essential for fetal development.
By the end of the first trimester the pituitary gland is completely formed remaining connected to the hypothalamus by the pituitary stalk (infundibulum), allowing the integration of signals from the brain and regulation of various endocrine functions. This dual-origin structure and function are what make the pituitary gland a unique and critical component of the endocrine system, acting as a bridge between the nervous and endocrine systems.
Pituitary can differentiate into different types of hormone-producing cells, with a great number specialising as .
All of the functions of the pituitary gland can be adversely affected by an over- or under-production of associated hormones.
The pituitary gland is important for mediating the stress response, via the hypothalamic–pituitary–adrenal axis (HPA axis). Critically, pituitary gland growth during adolescence can be altered by early life stress such as childhood maltreatment or maternal dysphoric (depressive) behavior.
It has been demonstrated that, after controlling for age, sex, and BMI, larger quantities of DHEA and DHEA-S tended to be linked to larger pituitary volume. Additionally, a correlation between pituitary gland volume and social anxiety subscale scores was identified which provided a basis for exploring mediation. Again controlling for age, sex, and BMI, DHEA and DHEA-S have been found to be predictive of larger pituitary gland volume, which was also associated with increased ratings of social anxiety. This research provides evidence that pituitary gland volume mediates the link between higher DHEA(S) levels (associated with relatively early adrenarche) and traits associated with social anxiety. Children who experience early adrenarcheal development tend to have larger pituitary gland volume compared to children with later adrenarcheal development.
The expression glandula pituitaria is still used as official synonym beside hypophysis in the official Latin nomenclature Terminologia Anatomica.Federative Committee on Anatomical Terminology (FCAT) (1998). Terminologia Anatomica. Stuttgart: Thieme In the seventeenth century the supposed function of the pituitary gland to produce nasal mucus was debunked. The expression glandula pituitaria and its English equivalent pituitary gland can only be justified from a historical point of view.Triepel, H. (1927). Die anatomischen Namen. Ihre Ableitung und Aussprache. Anhang: Biographische Notizen.(Elfte Auflage). München: Verlag J.F. Bergmann. The inclusion of this synonym is merely justified by noting that the main term hypophysis is a much less popular term.International Anatomical Nomenclature Committee (1966). Nomina Anatomica. Amsterdam: Excerpta Medica Foundation, p. 62
The German anatomist Samuel Thomas von Sömmerring coined the name hypophysis. This name consists of ὑπό ('under') and φύειν ('to grow'). In later Greek ὑπόφυσις is used differently by Greek physicians as outgrowth. Sömmering also used the equivalent expression appendix cerebri, with appendix as appendage. In various languages, Hirnanhang in German language and hersenaanhangselPinkhof, H. (1923). Vertalend en verklarend woordenboek van uitheemsche geneeskundige termen. Haarlem: De Erven F. Bohn. in Dutch language, the terms are derived from appendix cerebri.
The division of the pituitary described above is typical of , and is also true, to varying degrees, of all . However, only in mammals does the posterior pituitary have a compact shape. In lungfish, it is a relatively flat sheet of tissue lying above the anterior pituitary, but in , , and , it becomes increasingly well developed. The intermediate lobe is, in general, not well developed in any species and is entirely absent in birds.
The structure of the pituitary in fish, apart from the lungfish, is generally different from that in other animals. In general, the intermediate lobe tends to be well developed, and may equal the remainder of the anterior pituitary in size. The posterior lobe typically forms a sheet of tissue at the base of the pituitary stalk, and in most cases sends irregular finger-like projection into the tissue of the anterior pituitary, which lies directly beneath it. The anterior pituitary is typically divided into two regions, a more anterior rostral portion and a posterior proximal portion, but the boundary between the two is often not clearly marked. In , there is an additional, ventral lobe beneath the anterior pituitary proper.
The arrangement in , which are among the most primitive of all fish, may indicate how the pituitary originally evolved in ancestral vertebrates. Here, the posterior pituitary is a simple flat sheet of tissue at the base of the brain, and there is no pituitary stalk. Rathke's pouch remains open to the outside, close to the nasal openings. Closely associated with the pouch are three distinct clusters of glandular tissue, corresponding to the intermediate lobe, and the rostral and proximal portions of the anterior pituitary. These various parts are separated by meninges membranes, suggesting that the pituitary of other vertebrates may have formed from the fusion of a pair of separate, but associated, glands.
Most armadillos also possess a neural secretory gland very similar in form to the posterior pituitary, but located in the tail and associated with the spinal cord. This may have a function in osmoregulation.
There is a structure analogous to the pituitary in the octopus brain.
The intermediate lobe is, in general, not well developed in tetrapods, and is entirely absent in birds.Romer, Alfred Sherwood (1977). 003910284X, Holt-Saunders International. 003910284X
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