Caveolae are small, flask-shaped invaginations found in the plasma membrane of many cell types. They play a crucial role in various cellular processes, including endocytosis, signal transduction, and lipid regulation. Caveolae are rich in proteins, such as caveolins, which help maintain their structure and function. These structures are particularly abundant in adipocytes (fat cells) and endothelial cells (cells lining blood vessels). Caveolae facilitate the uptake of molecules and contribute to the organization of signaling pathways, making them important for maintaining cellular homeostasis and responding to external stimuli.