This confocal image shows microfilaments (in green) and cell nuclei (in red) of developing wood cells in poplar. In plants, the cytoskeleton is specialised for particular functions. This image shows the cells that will increase in length to run from the outside of the tree's trunk towards the inside (the ray cells, which are observed looking like the spokes of a wheel looking down at a cut tree stump) along with other cells that will increase in length parallel to trunk. In both cases the direction of cell extension is mirrored by the arrangement of the microfilaments.