Time-lapse study of the effect of Sarm1 knockdown on dendrite morphology. Cultured hippocampal neurons were transfected with Sarm1i¹ or pSuper at 13 DIV. The images were recorded 10 min/frame for 24 h starting from 15 DIV. (A) Representative images of a control neuron (pSuper; top) and a Sarm1 knockdown neuron (Sarm1i; bottom). Bar, 30 µm. (B) Enlarged local images of neurons transfected with Sarm1i¹. Arrowheads indicate a continuously retracting dendrite, whereas the arrows denote a dendrite that outgrew first and then retracted. Bar, 5 µm. (C) The relative dendrite length of individual neurons during the recording period. (D) The growth and pruning rates of individual neurons; the rates of individual neurons are connected with a line. (E) The means of the ratio of growth rate to pruning rate (n = 5). Error bars indicate mean values ± SEM. **, P < 0.005.