Figure 3. Embryonic dentate Hopx⁺ progenitors adopt adult RGL-like properties during early postnatal development.

(A-B) Hopx⁺ progenitors adopt a radial morphology and a quiescent state during the first postnatal week. Shown in (A) are confocal images of Mcm2⁺Hopx⁺Nestin⁺ progenitors in the dentate gyrus at P3, P7 and P60. Boxed area at P3 is shown in a higher magnification. Scale bars: 40 μm. Also See Figure S3A. Shown in (B) is quantification of the percentage of Mcm2⁺ cells among all Hopx⁺Nestin⁺ progenitors in the dentate gyrus. Values represent mean ± SEM (n = 3–4 dentate gyri; ***p < 0.001; One-way ANOVA with Tukey post-hoc test).

(C-D) Birth dating of Hopx⁺ adult RGLs. EdU was administered on a single day shown on the x-axis in (D), followed by a chase period until analysis at P30. Shown in (C) are confocal images of EdU⁺ RGLs after EdU injection at P3. Arrows indicate EdU⁺ nuclei. Scale bar: 20 μm. Shown in (D) is quantification of the proportion of Hopx⁺Nestin⁺ RGLs in the dentate gyrus that retained EdU at P30 from injection at different times during development (x-axis). Also see Figure S3F. Values represent mean ± SEM (n = 4–5 dentate gyri).

(E-H) Hopx-CreER^T2::mTmG mice received a single injection of tamoxifen at P7 for clonal lineage-tracing (See Table S1). Shown in (E) are confocal images of a clone at 3 dpi consisting of a single Nestin⁺Mcm2⁻ RGL. Arrow indicates Mcm2⁻ nucleus and arrowhead indicates Nestin⁺ radial process. Scale bar: 20 μm. Shown in (F) are confocal images of two clones at 53 dpi, one containing a single RGL (left panels), and the other containing mature neurons (right panels). Scale bars: 20 μm. Also shown are quantifications of the percentage of clones consisting of a single RGL (G; similar to Figure 1C) and of activated clone compositions (H; similar to Figure 1E). Values represent mean ± SEM (n = 6 dentate gyri).

(I-K) Hopx-CreER^T2::mTmG mice were given a single injection of tamoxifen at P7 for population fate mapping (See Table S1). Shown in (I) is the experimental paradigm. Shown in (J) are confocal images of GFP⁺ cells in the dentate gyrus. Note Nestin staining on blood vessels. Scale bars: 100 μm. Shown in (K) is quantification of the composition of the GFP⁺ population in the dentate gyrus. Similar to Figure 1J. Values represent mean ± SEM (n = 4 dentate gyri).

See also Figure S3 and Table S1.