Modeling Planarian Regeneration: A Primer for Reverse-Engineering the Worm
Figure 2
Diagrams of the main planarian regeneration experiments found in the literature.
(A) Cutting experiments amputate part of the planarian body (shadowed); normally, a complete regenerated worm results within 1–2 weeks. (B) Transplantation of diverse parts also regenerates into a complete worm. (C) Planarians degrowth when starved; they restore their original size upon feeding. (D) Octanol blocks gap junction communication between the worm cells; a trunk fragment treated with octanol regenerates into a double-headed worm. (E) A post-pharyngeal fragment treated with octanol and with the nerve cords partially amputated regenerates into a quadruple-headed worm. (F) An external electric field applied to a trunk fragment disturbs AP polarity during regeneration when the anode is located in the head wound; low-intensity currents cause double-headed worms, whereas high-intensity currents cause reversed-polarity worms. (G) The drugs ivermectin (IVM) and SCH-28080 (SCH) disturb the ion pumps in the worm cells, altering their membrane voltage. IVM causes cell depolarization (more positive) and trunk fragments to regenerate into double-headed worms; SCH causes cell hyperpolarization (more negative) and trunk fragments to regenerate into worms with no heads.