The choroid plexus is formed by a complex structure consisting of specialized cells and blood vessels. It is primarily composed of three main components:
Choroidal epithelial cells: The choroid plexus is lined by a layer of specialized epithelial cells called choroidal epithelial cells. These cells have finger-like projections known as microvilli that increase their surface area for fluid exchange. Choroidal epithelial cells are responsible for the production and secretion of cerebrospinal fluid (CSF). They actively transport ions, nutrients, and other substances from the blood into the CSF, while also filtering and regulating its composition.
Capillaries: The choroid plexus contains a dense network of blood vessels known as choroidal capillaries. These capillaries supply blood to the choroid plexus and play a crucial role in the exchange of substances between the blood and the CSF. The choroidal capillaries have fenestrations (small pores) that allow the passage of certain molecules and ions, facilitating the secretion and filtration processes carried out by the choroidal epithelial cells.
Connective tissue: The choroid plexus is supported by a framework of connective tissue that helps maintain its structure and integrity. This connective tissue provides a structural scaffold for the choroidal epithelial cells and blood vessels within the choroid plexus.
Together, the choroidal epithelial cells, choroidal capillaries, and connective tissue form the choroid plexus. This complex structure allows for the production, filtration, and regulation of cerebrospinal fluid within the ventricles of the brain.