C. elegans

A) A C. elegans worm with the anchor cell (marked green with fluorescent proteins) and the three closest vulva cells.
B) Researchers found a large variation in the position of the anchor cell ( purple) relative to the vulva cells in the development of C. elegans.
On the left, the cell nearest to the anchor cell (red violet) receives the strongest signal to acquire the primary fate. It subsequently sends signals to its neighbours (the so-called Notch signal), which ensures that these develop into secondary cells (blue).
On the right, two cells have a virtually equal chance of becoming the primary cell type. The cell that is slightly closer creeps towards the anchor cell and sends a slightly stronger Notch signal to the neighbouring cell. The combination of these two effects ensures canalisation: despite the initial variation, the final pattern is the same as that in the left-hand part of the figure.