Extended Data Fig. 1. Morphologically complex striatal astrocytes lose their complexity upon dissociation.

a. Representative image of S100β immunostaining in a mouse coronal section containing the striatum. Subpanels show representative striatal astrocytes sparsely expressing cytosolic tdTomato fluorescent protein after GfaABC₁D tdTomato AAV microinjection. The experiment was replicated five times. b. Striatal astrocyte sparsely labeled with tdTomato and co-stained with nuclear marker DAPI and neuronal marker NeuN. Quantification shows DAPI+ nuclei and NeuN+ cell bodies found in a single tdTomato+ astrocyte’s territory. Mean and SEM are shown; (n = 12 tdTomato+ cells per group from 4 animals). c. In situ Lucifer yellow iontophoretically filled striatal astrocyte from 8-week-old mice. Right panel shows GFP+ striatal astrocytes after dissociation for fluorescence activated cell sorting (FACS) from 8-week-old mice. d. Quantification of territory area, number of primary branches, and number of secondary branches showed that dissociated astrocytes display decreased cellular complexity. Mean and SEM are shown; (n = 40 cells from 15 mice for Lucifer yellow and n = 164 cells from 8 mice for Aldh1l1-GFP, respectively; territory area and number of primary branches: two-tailed student’s unpaired t-test, P = 0.0002; number of secondary branches: two-tailed one-sample t-test, P = 0.003).