Annual Plant Reviews, Volume 18 Plasmodesmata are the narrow channels that link plant cells together, acting as intercellular cytoplasmic bridges to facilitate communication and transport of materials between cells. While previously it was thought that they were merely passive tunnels for small solute transport between cells, there are now fervent debates about the structure, composition and active transport dynamics of these channels. This volume provides a broad, state-of-the-art review of this highly topical area, providing a point of entry to the detailed literature.