Figure 1.

Expression and functional activity of BMP signaling components in the adult SEZ. A–H, In situ hybridization of mRNA transcripts of BMP ligands (A–D), the extracellular inhibitor noggin (E), BMP receptor II (F), the central signaling mediator Smad4 (G), and the downstream target Id3 (H). I–O, Fluorescent micrographs of double immunostainings for the BMP ligand specific phosphorylated Smads 1/5/8 (p-Smad1/5/8) with different cell type-specific antigens in the adult SEZ as indicated in the panels. The arrows in the panels indicate double-labeled cells. Note that p-Smad1/5/8 is contained mostly in GFAP+ (I, N) and some fast proliferating BrdU+ cells (J), but not in DCX+ neuroblasts (K). p-Smad1/5/8 also colocalizes with the transcription factor Dlx2 (L), but not Olig2 (M) (note that there are p-Smad1/5/8+ cells also in the choroid plexus). O, Fluorescent micrograph depicting the colocalization of p-Smad1/5/8 with BrdU in BrdU-retaining cells of the SEZ. The quantitative composition of the p-Smad1/5/8-immunopositive cell pool is depicted in the pie diagram in P. LV, Lateral ventricle; Str, striatum; ChP, choroid plexus. The orientation of the sections is indicated under D, depicting dorsal; V, depicting ventral; R, depicting rostral; and C, depicting caudal. Scale bars: (in H) A–H, 100 μm; (in M) I–O, 70 μm.