FIGURE 1.

Attenuated spontaneous mobility of dextran‐positive vesicles in NB+ astrocytes. (a), (b) confocal micrographs of morphologically distinct nonarborized serum (a; DMEM+) and arborized (b; NB+) astrocytes labeled with membrane styryl dye FM4‐64. (c), (d) the relative frequency distribution (in %) of the cell shape factor (=4 × π × S/p², where S represents the surface area and p the cell perimeter) values calculated in DMEM+ astrocytes (c) and NB+ astrocytes (d). e, f confocal micrographs of DMEM+ astrocytes (e) and NB+ astrocytes (f) with numerous endocytotic vesicles that internalized fluorescent dextran (Dex488, green). Scale bars, 10 μm. (g), (h) trajectories of Dex488‐positive vesicles (n = 30) reconstructed for a 15 s epoch in DMEM+ astrocytes (g) and NB+ astrocytes (h). Note the less elongated vesicle tracks in NB+ astrocyte. Scale bars, 10 μm. (i), (j), (k), (l) track length (TL; (i)), maximal displacement (MD; (j)), directionality index (DI; (k)), and speed (l) of Dex488‐positive vesicles in DMEM+ and NB+ astrocytes. Note that all parameters of vesicle mobility (TL, MD, DI, and speed), are diminished in NB+ astrocytes. The numbers at the top and at the bottom of the bars (mean ± SEM) indicate the number of vesicles and cells analyzed, respectively. ***p < .001 (Mann–Whitney U‐test)