Pars intermedia
Encyclopedia
Pars intermedia is the boundary between the anterior and posterior lobes of the pituitary. It contains three types of cells - basophil
s, chromophobe
s, and colloid
-filled cyst
s. 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.
Anterior pituitary basophil
An anterior pituitary basophil is a type of cell in the anterior pituitary which manufactures hormones.It is called a basophil because it readily takes up base, and typically stains a relatively deep blue or purple....
s, chromophobe
Chromophobe
The term chromophobe refers to histological structures which do not stain readily, and thus appear more relatively pale under the microscope—hence their "fear" of "color" .-Cancer:...
s, and colloid
Colloid
A colloid is a substance microscopically dispersed evenly throughout another substance.A colloidal system consists of two separate phases: a dispersed phase and a continuous phase . A colloidal system may be solid, liquid, or gaseous.Many familiar substances are colloids, as shown in the chart below...
-filled cyst
Cyst
A cyst is a closed sac, having a distinct membrane and division on the nearby tissue. It may contain air, fluids, or semi-solid material. A collection of pus is called an abscess, not a cyst. Once formed, a cyst could go away on its own or may have to be removed through surgery.- Locations :* Acne...
s. The cysts are the remainder of Rathke’s pouch.
In human fetal
Fetus
A fetus is a developing mammal or other viviparous vertebrate after the embryonic stage and before birth.In humans, the fetal stage of prenatal development starts at the beginning of the 11th week in gestational age, which is the 9th week after fertilization.-Etymology and spelling variations:The...
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.