Pars intermedia: Difference between revisions

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'''Pars intermedia''' is a part of the [[pituitary gland]] that is situated between the [[anterior pituitary]] and the [[posterior pituitary]]. It is also known as the intermediate lobe of the pituitary gland. The pars intermedia is responsible for the production of [[melanocyte-stimulating hormone]] (MSH), which plays a crucial role in the pigmentation of the skin and hair in mammals.
{{Short description|Section of the pituitary gland}}
{{Use dmy dates|date=October 2023}}
 
The '''pars intermedia''' is a part of the [[pituitary gland]], which is an important endocrine organ located at the base of the brain. The pituitary gland is divided into three distinct parts: the [[anterior pituitary]] (adenohypophysis), the [[posterior pituitary]] (neurohypophysis), and the pars intermedia. The pars intermedia is situated between the anterior and posterior lobes of the pituitary gland.


==Structure==
==Structure==
The pars intermedia is a thin layer of tissue that separates the anterior and posterior lobes of the pituitary gland. It is composed of [[melanotrophs]], which are cells that produce and secrete MSH. The pars intermedia is more prominent in animals than in humans, where it is often rudimentary or absent.
The pars intermedia is a thin layer of cells that is often considered part of the anterior pituitary. It is composed of [[basophilic cells]] and is less developed in humans compared to other species. In some animals, such as fish and amphibians, the pars intermedia is more prominent and plays a significant role in physiological processes.
 
[[File:Human pituitary gland.jpg|thumb|right|Diagram of the human pituitary gland showing the pars intermedia.]]


==Function==
==Function==
The primary function of the pars intermedia is the production and secretion of MSH. This hormone stimulates the production and release of melanin, the pigment responsible for the color of the skin, hair, and eyes in mammals. MSH also has effects on appetite and sexual behavior, although these functions are less well understood.
The primary function of the pars intermedia is the production of [[melanocyte-stimulating hormone]] (MSH), which is involved in the regulation of skin pigmentation. MSH stimulates the production and release of [[melanin]] by melanocytes in the skin and hair. In humans, the role of MSH is less pronounced, but it is still involved in the regulation of appetite and energy homeostasis.
 
==Development==
During embryonic development, the pituitary gland forms from two distinct ectodermal tissues: the [[Rathke's pouch]] and the infundibulum. The pars intermedia originates from Rathke's pouch, which also gives rise to the anterior pituitary. As development progresses, the pars intermedia becomes a thin layer of cells sandwiched between the anterior and posterior lobes.


==Clinical significance==
==Clinical Significance==
Abnormalities in the pars intermedia can lead to a variety of medical conditions. For example, [[Cushing's disease]] in dogs is often caused by a tumor in the pars intermedia. This results in an overproduction of MSH, leading to symptoms such as darkening of the skin and hair loss. In humans, a rare condition known as [[Nelson's syndrome]] can occur following the surgical removal of the adrenal glands, leading to an overproduction of MSH and darkening of the skin.
In humans, disorders of the pars intermedia are rare. However, in some animals, such as horses, dysfunction of the pars intermedia can lead to conditions like [[Equine Cushing's disease]], also known as pituitary pars intermedia dysfunction (PPID). This condition is characterized by an overproduction of hormones, leading to symptoms such as increased coat length, weight loss, and laminitis.


==See also==
==Related pages==
* [[Pituitary gland]]
* [[Pituitary gland]]
* [[Anterior pituitary]]
* [[Anterior pituitary]]
* [[Posterior pituitary]]
* [[Posterior pituitary]]
* [[Melanocyte-stimulating hormone]]
* [[Melanocyte-stimulating hormone]]
* [[Cushing's disease]]
* [[Endocrine system]]
* [[Nelson's syndrome]]


[[Category:Endocrine system]]
[[Category:Endocrine system]]
[[Category:Pituitary gland]]
[[Category:Human anatomy]]
 
{{stub}}
<gallery>
File:Pars_intermedia_Gray1181.png|Pars intermedia
File:Pituitary_gland_histology_2014.jpg|Pituitary gland histology
</gallery>
== Pars_intermedia ==
<gallery>
File:Gray1181.png|Pars intermedia
File:Pituitary_gland_histology_2014.jpg|Pituitary gland histology 2014
</gallery>

Revision as of 17:44, 18 February 2025


The pars intermedia is a part of the pituitary gland, which is an important endocrine organ located at the base of the brain. The pituitary gland is divided into three distinct parts: the anterior pituitary (adenohypophysis), the posterior pituitary (neurohypophysis), and the pars intermedia. The pars intermedia is situated between the anterior and posterior lobes of the pituitary gland.

Structure

The pars intermedia is a thin layer of cells that is often considered part of the anterior pituitary. It is composed of basophilic cells and is less developed in humans compared to other species. In some animals, such as fish and amphibians, the pars intermedia is more prominent and plays a significant role in physiological processes.

File:Human pituitary gland.jpg
Diagram of the human pituitary gland showing the pars intermedia.

Function

The primary function of the pars intermedia is the production of melanocyte-stimulating hormone (MSH), which is involved in the regulation of skin pigmentation. MSH stimulates the production and release of melanin by melanocytes in the skin and hair. In humans, the role of MSH is less pronounced, but it is still involved in the regulation of appetite and energy homeostasis.

Development

During embryonic development, the pituitary gland forms from two distinct ectodermal tissues: the Rathke's pouch and the infundibulum. The pars intermedia originates from Rathke's pouch, which also gives rise to the anterior pituitary. As development progresses, the pars intermedia becomes a thin layer of cells sandwiched between the anterior and posterior lobes.

Clinical Significance

In humans, disorders of the pars intermedia are rare. However, in some animals, such as horses, dysfunction of the pars intermedia can lead to conditions like Equine Cushing's disease, also known as pituitary pars intermedia dysfunction (PPID). This condition is characterized by an overproduction of hormones, leading to symptoms such as increased coat length, weight loss, and laminitis.

Related pages