Fig. 3.

Rapid dendritic motility results in extensive remodeling while maintaining the overall size and complexity of the dendritic arbor. A, The z-projection of the confocal image stack capturing the entire arbor of an E12 ganglion cell at the start of a time-lapse recording. This image thus represents the three-dimensional reconstruction of the arbor at one time point.B, C, Difference images generated by digitally subtracting the image in A from thez-projection of an image stack captured 1 hr later. Theblackareas in B indicate dendritic structures that have been added or have undergone extension in the intervening hour, whereas the blackareas in C indicate structures that have been eliminated or have undergone retraction. The whiteareas in both B and Cindicate dendritic structures that were unchanged. Note that the relative amount and distribution of the structures added (B) and taken away (C) are approximately balanced. D, Plot of the total number of branch points and the number of branch points in the central and peripheral halves of the dendritic tree. Central and periphery halves of the tree are separated by the line bisecting the midpoints of radii extending from the soma to the perimeter of the arbor.E, Histogram representing the change in the number of branch points with time. Whitebars(addition) indicate the number of novel branch points added at that time point (i.e., those not observed at the preceding time point), whereas hatchedbars(elimination) indicate those eliminated since the preceding time point. Darkbars(net) indicate the difference between additions and eliminations. F, Percent change in the total dendritic length (TDL) of four cells (each cell represented by adifferentsymbol) as a function of time, illustrating the relative constancy in the total length despite extensive dendritic movements occurring across this period.