KT5823 inhibits novel chemical synapse formation without affecting neurite extension. Maximum-intensity Z projections of confocal images of fluorescently labeled B1 and B2 neurons 2 d after axonal injury and treatment with KT5823 (Ai, B1, Aii, B2). Aiii, Average total neurite length of B1 and B2 neurons 2 d after axonal injury under control conditions (DIV2+) and in the presence of KT5823 (+ KT5823). Groups were compared using NK tests (n.s. p > 0.05). B, Percentage of specific cell pairs showing electrical coupling 2 d after axonal injury under the two experimental conditions (DIV2+, + KT5823) outlined above. n is indicated on the bars. C, Percentage of specific cell pairs showing excitatory chemical coupling 2 d after axonal injury under the two experimental conditions (DIV2+, + KT5823) outlined above. n is indicated on the bars. Scale bar in Ai, 100 μm.