Fig. 2

Single-cell regeneration in Stentor coeruleus a A living Stentor cell. The oral apparatus, located towards the upper left of the image, is a large ring of cilia that collects food particles from the surrounding pond water. At the other end of the cell, a holdfast attaches the cell to the surface of pond plants. b Regeneration after bisection of a Stentor cell. The panel on the left shows the longitudinal strips of blue pigment that serve as markers for cellular pattern. When a Stentor cell is cut in half with a glass needle, as indicated by the dotted orange line, each half initially heals its wounds to prevent cytoplasm from leaking out (middle panels) and then within approximately one day, regenerates a complete cell (right panel), with the anterior half regenerating a new holdfast, and the poster half regenerating a new oral apparatus. Both halves are able to regenerate because the cell contains a long polyploid macronucleus running down the length of the cell, such that when a cell is cut, both halves retain many copies of the genome