Muscle and neuronal guidepost-like cells facilitate planarian visual system regeneration

Guiding regeneration Many adult organisms can regenerate neural circuits after injury. However, it is not clear which guidance mechanisms operate to promote axon path finding in the adult. Scimoneet al. addressed this question by investigating regeneration of the planarian visual system (see the Perspective by Roberts-Galbraith). Distinct muscle cell populations were found in close association with photoreceptor axons that, together with a neuron class, facilitated visual system assembly after diverse injuries or eye transplantations. These cells exhibited features similar to embryonic guidepost cells and were specified independently of eyes in precise locations by the action of adult positional information cues. Absence of these guidepost-like cells was associated with defective neuronal wiring in regeneration.Science , this issue p.eaba3203 ; see also p.1428