cytoneme

A cytoneme is a long, thin cellular projection that extends from a cell. These projections are not fixed structures but are dynamic, constantly extending, retracting, and interacting with other cells and the extracellular environment. Cytonemes are involved in a variety of cellular processes, including cell-to-cell communication, tissue development, and immune responses.

The precise mechanisms by which cytonemes form and function are still under investigation. However, it is known that they are composed of actin filaments and are often covered by a plasma membrane. The direction of cytoneme extension can be guided by chemical signals present in the extracellular space. Once a cytoneme makes contact with a target cell or structure, it can facilitate the transfer of molecules, such as signaling proteins or even organelles.

In developmental biology, cytonemes play a crucial role in establishing cell-cell signaling networks. For example, they have been observed extending from developing neurons to target cells, delivering signals that guide axonal growth and synapse formation. In the immune system, cytonemes are involved in the interaction between immune cells, allowing for the efficient exchange of information and coordination of immune responses. Research into cytonemes continues to reveal their diverse roles and their importance in maintaining cellular and tissue homeostasis.