Figure 4: Removal of extracellular Ca²⁺ blocks axonal fragmentation in vivo.

(a) Single time points (montaged maximum intensity projection) from a multiphoton in vivo time-lapse showing axonal calcium levels after contusion in the absence of extracellular Ca²⁺ (top; ‘+EGTA’: 0 Ca²⁺ aCSF containing 25 mM EGTA—these high levels were required because of restricted in vivo access) and after return to normal Ca²⁺ (bottom; ‘aCSF w/Ca²⁺’). For colour look-up table cf. Fig. 2a. (b) Population data of Ca²⁺ (left) and morphological changes (right) from such experiments (170 axons, 6 Thy1-TNXXL mice; for a comparable control, cf. Fig. 5c,e). Scale bar in a, 20 μm.