Time-lapse imaging of membrane extension. fGFP neurospheres were added in shiverer myelinating cultures and time-lapse imaging was performed on 22 DIV for 21 hours with 3 min time intervals. Ai -vi) Time-lapse sequence of a fGFP-positive cell moving dynamically like a wave towards a thin fGFP-positive shiverer axon (red arrows). During the recordings, numerous intracellular, round structures (green arrows) were imaged displaying a dynamic activity of the membrane of the fGFP-positive astrocyte-like cells. See Additional file 1, from 2 separate experiments.