Movie 2.

Cyclopamine-mediated inhibition of Smo induced aberrant dI1 axon guidance at the contralateral floorplate border only with a 4-hour delay. Twenty-four hours of time-lapse recording of the ventral midline of ex vivo spinal cords shows Math1::tdTomato-F-positive dI1 axons (black) at the contralateral floorplate border in a Cyclopamine-treated sample (Cyclop.). Axons that were crossing or about to exit the floorplate (filled arrowheads) at the beginning of the recording/inhibition showed a normal trajectory with a rostral turn. However, most of the axons that were not yet in the floorplate when Cyclopamine was added showed aberrant navigation at the exit site (open arrowheads). Rostral is up.