Figure 4. Bystander cell death is induced after direct contact between free-floating cell corpses and healthy, migrating neurons.

(A) The cell corpse (yellow arrowhead) is initially connected to the healthy neuron's (red star) axon (0 h), but apoptosis is not induced until the two cell bodies make contact. After the cell body contacts the cell corpse (1 h 10 min, yellow arrowhead), the healthy neuron (red star) rounds up (1 h 20 min), blebs (1 h 30 min) and dies (2 h). First picture is taken 5 h and 50 minutes after injury and time indicated in the pictures is time lapsed after the first image. Scale bars = 10 µm, the dashed lines represent the scratch. (B) To analyze the frequency of bystander cell death, all neurons in 4 different time-lapse films were tracked. In total we found 26 neurons that came in contact with free-floating dead cells. Of these 26 neurons, 21 neurons (80.8%) died within the experiment. The squares represent the survival time for each of these 21 neurons after contact with the dead cell and lines represent the median±interquartile range.