NCIt definition : A small pocket, vesicle, cave, or recess communicating with the outside of a cell
and extending inward, indenting the cytoplasm and the cell membrane. Such caveolae
may be pinched off to form free vesicles within the cytoplasm. They are considered
to be sites of uptake of materials into the cell, expulsion of materials from the
cell, or sites of addition or removal of cell (unit) membrane to or from the cell
surface.;