The phorbol ester TPA dramatically inhibits planarian regeneration

The effect of phorbol ester TPA (12-O-tetradecanoylphorbol-13-acetate) on head regeneration in decapitated planarians ( Dugesia lugubris s.1.) has been studied. TPA-treatment soon after head amputation dramatically inhibited the regenerative process. Ultrastructural analysis revealed that the migration of fixed parenchymal cells (FPCs) to the wound area was strongly activated by TPA. FPCs interacted with various types of cells inducing lysis and phagocyting cell debris. The resulting fluid was removed through diaphanous protrusions appearing at the level of the wound zone. Moreover the close association of FPCs with neoblastlike cell clusters in the parenchyma indicated their possible role in the modulation of neoblast migration.