Planarian Regeneration: Wnt/β-catenin Polarity Switch

Planarian flatworms can regrow a whole animal from a small body fragment because pools of adult pluripotent stem cells — neoblasts — swarm the wound and build a blastema, then read a graded Wnt/β-catenin signal to decide whether that blastema becomes a head or a tail. This simulator renders a segmented 3D worm body out of instanced cells, lets you cut it anywhere along its length, and grows a real logistic-curve blastema at each wound whose fate is computed from the same signaling logic used in the lab: normal signaling regenerates the correct missing part, suppressing β-catenin produces the textbook double-headed phenotype, and boosting it produces a double-tailed one.