FIG. 2.

Immunohistochemical analysis of C1qR1⁺ cells. (A–H) Expression and localization of C1qR1 protein in the developing cerebral cortex at E14.5. Immunohistochemistry of cerebral cortex at low magnification (10×) (A–D) and high magnification (40×) (E–H). Labeling for DAPI in (A) and (E), Nestin in (B) and (F), C1qR1 in (C) and (G), and Merged in (D) and (H). The boxes in (B–D) span the ventricular zone (VZ) from the apical to basal region and are shown at higher magnification in (F–H). The inserts in (F–H) show optical zoom of the boxed areas. C1qR1 is localized in the membrane throughout the neural progenitor cells of the cortical ventricular zones (VZ and subventricular zone) with an intense staining in the VZ. The insert in (H) shows the cellular colocalization of C1qR1 and nestin (as seen in yellow). Scale bars (A) = 100 μm and (E) = 40 μm. (I) Cells obtained from freshly dissociated embryonic brain were stained with anti-C1qR1-PE. Unsorted, C1qR1⁺, and C1qR1⁻ cells were sorted and plated at 667 cells/mL. The number of primary neurospheres formed in the presence of EGF and FGF2 was counted 5 days later. Data are presented as mean ± SEM from three experiments. *P < 0.05, **P < 0.01. (J) Bright-field image of secondary neurosphere generated from C1qR1⁺ cells. Scale bar = 100 μm, at 4× magnification. (K–N) C1qR1⁺ population gives rise to neurospheres that differentiate into oligodendrocytes (O4; green), neurons (βIII-tubulin; red), and astrocytes (GFAP; gray). Scale bar = 50 μm.