Caveolins and Caveolae: Roles in Signaling and Disease Mechanisms - Advances in Experimental Medicine and Biology 2012 edition

Using modern electron microscopy techniques, caveolae can be observed as omega-shaped invaginations of the plasma membrane, fully-invaginated caveolae, grape-like clusters of interconnected caveolae (caveosome), or as transcellular channels as a consequence of the fusion of individual caveolae.