cytoneme

Cytonemes are thin, cellular projections that are specialized for exchange of signaling proteins between cells. Cytonemes emanate from cells that make signaling proteins, extending directly to cells that receive signaling proteins. Cytonemes also extend directly from cells that receive signaling proteins to cells that make them
A cytoneme is a type of filopodium - a thin, tubular extension of a cell’s plasma membrane that has a core composed of tightly bundled, parallel actin filaments. Filopodia can extend more than 100 µm and have been measured as thin as 0.1 µm and as thick as 0.5 µm. Cytonemes with a diameter of approximately 0.2 µm and as long as 80 µm have been observed in the Drosophila wing imaginal disc