Pars intermedia

Pars intermedia
Median sagittal through the hypophysis of an adult monkey. (Pars intermedia labeled at bottom center.)
Details
Identifiers
Latin	pars intermedia adenohypophyseos
TA98	A11.1.00.004 A09.4.02.017
TA2	3858
TH	H3.08.02.2.00007
FMA	74632
Anatomical terminology [edit on Wikidata]

Pars intermedia is the boundary between the anterior and posterior lobes of the pituitary. It contains colloid-filled cysts and two types of cells - basophils and chromophobes. The cysts are the remainder of Rathke's pouch. As technically part of the anterior pituitary, it separates the posterior pituitary and pars distalis. It is composed of large, pale cells that encompass the aforementioned colloid-filled follicles.^[1]

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.

References

External links

• Histology image: 14001loa – Histology Learning System at Boston University
• Histology image: 14101loa – Histology Learning System at Boston University
• Histology image: 38_11 at the University of Oklahoma Health Sciences Center
• UIUC Histology Subject 991

This page was last edited on 30 April 2024, at 15:57