My watch list  

Pars intermedia

Pars intermedia
Median sagittal through the hypophysis of an adult monkey. (Pars intermedia labeled at bottom center.)
Latin pars intermedia adenohypophyseos
Gray's subject #275 1275
Dorlands/Elsevier p_07/12616939

Pars intermedia is the boundary between the anterior and posterior lobes of the pituitary. It contains three types of cells - basophils, chromophobes, and colloid-filled cysts. The cysts are the remainder of Rathke’s pouch.

In human fetal life, this area produces melanocyte stimulating hormone or MSH which causes the release of melanin pigment in skin melanocytes (pigment cells). However, the pars intermedia is normally either very small or entirely absent in adulthood.

In lower vertebrates (fish, amphibians) MSH from the pars intermedia is responsible for darkening of the skin, often in response to changes in background color. This color change is due to MSH stimulating the dispersion of melanin pigment in dermal (skin) melanophore cells.

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Pars_intermedia". A list of authors is available in Wikipedia.
Your browser is not current. Microsoft Internet Explorer 6.0 does not support some functions on Chemie.DE