Figure 5.
Tamoxifen induction reveals that plp-expressing progenitors are lineage restricted in vivo. A, B, Whole-mount X-gal staining of an E10.5 plp–CreERT2;R26R transgenic treated with tamoxifen at E9.5 (A) compared with an E10.5 plp–Cre;R26R embryo (B). Arrows indicate the bpd. C, Schematic representation of the tamoxifen injection protocol. Tamoxifen was injected into plp–CreERT2;Z/EG or plp–CreERT2;R26R pregnant mice at either E9.5 or E13.5 and analyzed at P0. D, E, Quantification of the percentage of neurons, glia, and ventricular cells obtained at P0 after tamoxifen injection at E9.5 and E13.5. Tamoxifen-injected animals were killed at birth (P0), and their brains were serially sectioned and double stained by immunofluorescence for GFP or β-gal and cell-type-specific markers (calretinin or NeuN for neurons and Olig-2 or S100β for glial cells). F, G, Confocal micrographs of single optical slices through cells in the diencephalon of plp–CreERT2;R26R newborn mouse injected with tamoxifen at E9.5 (F) and E13.5 (G) double stained by immunofluorescence for β-gal and either calretinin (F) or Olig-2 (G) and counterstained with Hoechst reagent. Merged images, individual channels, and orthogonal analysis show that β-gal-expressing cells are calretinin+ and Olig-2+ after tamoxifen injection at E9.5 (F) and E13.5 (G, arrows), respectively. Some β-gal+/Olig-2− cells with a bipolar morphology remain in the ventricular zone (arrowhead in G). Orthogonal images (ortho) show three-dimensional analysis of individual cells at specific sites marked by intersecting lines in the x-, y-, and z-axes. 3V, Third ventricle. Scale bar: A, B, 0.6 mm; F, G, 60 μm.