Anterior pituitary
Anterior pituitary gland | |
---|---|
Details | |
Precursor | Oral mucosa (Rathke's pouch) |
Artery | superior hypophyseal |
Vein | hypophyseal |
Identifiers | |
Latin | lobus anterior hypophysis |
MeSH | D010903 |
NeuroNames | 407 |
NeuroLex ID | birnlex_1581 |
TA98 | A11.1.00.002 |
TA2 | 3855 |
FMA | 74627 |
Anatomical terminology |
A major
The anterior pituitary regulates several
Structure
The
The anterior pituitary is composed of three regions:
- Pars distalis
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
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.
-
Microanatomy of the pars distalis showing chromophobes, basophils, and acidophils
-
Eosinophilic follicles are a common normal finding in the anterior pituitary.
- Pars tuberalis
- The photoperiod (length of day). The expression of this subunit is regulated by the secretion of melatonin in response to light information transmitted to the pineal gland.[2][3] Earlier studies have shown localization of melatonin receptors in this region.[4]
- Pars intermedia
- The pars intermedia (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.
Development
The anterior pituitary is derived from the
The pouch eventually loses its connection with the pharynx, 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 neuroectoderm.[5]
Function
The anterior pituitary contains five types of endocrine cell, and they are defined by the hormones they secrete:
Hormones secreted by the anterior pituitary are trophic hormones (Greek: trophe, "nourishment"). Trophic hormones directly affect growth either as hyperplasia or hypertrophy on the tissue it is stimulating. Tropic hormones are named for their ability to act directly on target tissues or other endocrine glands to release hormones, causing numerous cascading physiological responses.[5]
Hormone | Other names | Symbol(s) | Structure | Secretory cells | Staining | Target | Effect | |
---|---|---|---|---|---|---|---|---|
Adrenocorticotropic hormone | Corticotropin | ACTH | Polypeptide
|
Corticotrophs
|
Basophil
|
Adrenal gland | Secretion of glucocorticoid, mineralocorticoid and androgens | |
Thyroid-stimulating hormone | Thyrotropin | TSH | Glycoprotein | Thyrotrophs
|
Basophil
|
Thyroid gland
|
Secretion of thyroid hormones
| |
Follicle-stimulating hormone | - | FSH | Glycoprotein | Gonadotrophs
|
Basophil
|
Gonads
|
Growth of reproductive system | |
Luteinizing hormone | Lutropin | LH, ICSH | Glycoprotein | Gonadotrophs
|
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 | Lactotrophs
|
Acidophil
|
testes, prostate
|
Secretion of prostatic hyperplasia
|
ACTH secretion
|
Role in the endocrine system
Hypothalamic control
Hormone secretion from the anterior pituitary gland is regulated by hormones secreted by the
Other mechanisms
Aside from hypothalamic control of the anterior pituitary, other systems in the body have been shown to regulate the anterior pituitary's function.
Effects of the anterior pituitary
- Thermal homeostasis
The homeostatic maintenance of the anterior pituitary is crucial to our physiological well being. Increased plasma levels of
- Gonadal function
- HPA axis
Main article
The anterior pituitary plays a role in stress response.
Behavioral effects
- Development
- The release of GH, LH, and FSH are required for correct human development, including gonadal development.[12]
- Stress
- Operating through the amino acids), bone re-absorption (calcium mobilization), activation of the sympathetic nervous system response (fight or flight), anti-inflammatory effects, and inhibition of reproduction/growth.[12] When the anterior pituitary gland is removed (hypophysectomy) in rats, their avoidance learning mechanisms were slowed, but injections of ACTH restored their performance.[12] In addition, stress may delay the release of reproductive hormones such as luteinizing hormone (LH) and follicle-stimulating hormone (FSH).[15] 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.[16]
- Aging
- Operating through the
- Tactile responding
- It has been shown that infant mice who were stroked with a paintbrush (simulating motherly care) had more release and binding of growth hormone (GH) from the anterior pituitary gland.[12]
- Circadian rhythms
- Light information received by the eyes is transmitted to the
Clinical significance
Increased activity
Decreased activity
History
Etymology
The anterior pituitary is also known as the adenohypophysis, meaning "glandular undergrowth", from the Greek adeno- ("gland"), hypo ("under"), and physis ("growth").
Additional images
-
The anterior pituitary is the anterior, glandular lobe of the pituitary gland.
See also
- Triple bolus test
- Hypothalamic–pituitary–somatic axis
References
- ^ ISBN 9781451113419.
- PMID 23505514.
- S2CID 12723490.
- PMID 9414453.
- ^ ISBN 978-0878936205
- ^ Le Tissier, P.R; Hodson, D.J; Lafont C; Fontanaud P; Schaeffer, M; Mollard, P. (2012) Anterior pituitary cell networks. Front Neuroendocrinol. Aug; 33(3):252-66
- ^ 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.
- ^ Sone, M. and Osamura, R.Y. (2001) Leptin and the pituitary. Pituitary. Jan-Apr; 4(1-2): 15-23.
- ^ Hedge, G.A. (1977) Roles for the prostaglandins in the regulation of anterior pituitary secretion. Life Sci. Jan 1;20(1):17-33.
- ^ Racagni, G; Apud, J.A; Cocchi, D; Locatelli, V; Muller, E.E. (1982) GABAergic control of anterior pituitary hormone secretion. Life Sci. Aug 30;31(9):823-38.
- ^ Lin, M.T; Ho, L.T; and Uang, W.N. (1983) Effects of anterior pituitary hormones and their releasing hormones physiological and behavioral functions in rats. J. steroid Biochem. Vol. 19(1) 433-38.
- ^ ISBN 978-0878936205.
- S2CID 30175791.
- S2CID 24818312.
- ^ PMID 10844239.
- ^ Jung Eun Kim; Baik Kee Cho; Dae Ho Cho; Hyun Jeong Park (2013). "Expression of Hypothalamic-Pituitary-Adrenal Axis in Common Skin Diseases: Evidence of its Association with Stress-related Disease Activity". National Research Foundation of Korea. Retrieved 4 March 2014.
- S2CID 43285151.
- ISSN 1732-2693.
- PMID 17077948.
- S2CID 35481175.
- PMID 20258051.
Further reading
- Marieb, E. 2004. Human Anatomy and Physiology. Benjamin Cummings: New York.
- Wheater, P., Burkitt, H., Daniels, V. 1987. Functional Histology. Churchill Livingstone: New York.
External links
- Histology image: 14002loa – Histology Learning System at Boston University
- Embryology at unc.edu
- The Pituitary Network Association -- www.pituitary.org
- Secretion of hormones from the Anterior Pituitary Gland