The post-injury calcium response. The fluorescence intensity of a glial cell injected with Calcium Green 1 was measured before and after the cell was injured by crushing the connectives. An interval of >1 min (at break in time axis) occurred before the jump in fluorescence at 0 s. The calcium response in the area adjacent to the crush and up to several hundred micrometers away developed a calcium gradient during the first few minutes after the injury. As indicated in the inset, the calcium responses in regions 100-µm² square were measured every 25 µm from near the crush to 150 µm distant. All regions measured had a large increase in fluorescence immediately after the crush was made; intensity in the regions nearer to the crush continued to rise, whereas the regions farther away began to decline, thereby creating a larger spatial calcium gradient.