The caveola is a small (apparently) uncoated pit mostly found in the cell membrane of many highly differentiated mammalian cells, such as adipocytes, endothelial cells and muscle cells. These flask-shaped invaginations are defined by the presence of caveolins and contains a subset of lipid-raft components, including cholesterol and sphingolipids. Caveolae each comprise a caveolar bulb with a diameter of 60-80 nm, connected to an opening of fairly constant diameter. Caveolae might exists as single pits or can form a cluster of caveolae with non-caveolar membrane between the pits. In many tissues, and particularly in adipocytes, multiple caveolae are arranged around a central vacuolar domain. In developing muscle fibres, multiple caveolae are connected by a single neck to the cell membrane, producing large chains of interconnected caveolae. Another structural feature of caveolae in certain endothelia is the presence of a stomatal diaphragm, which consists of a central density and radial spikes, in the neck of the caveolae. Mature caveolae might be assembled in the Golgi apparatus. Caveolae can flatten out into the cell membrane, thereby loosing their caveolar identity.

Caveolae
Membrane microdomain
Plasmalemmal vesicle

› Cellular component

› caveola [ GO:0005901 ]