Smad3 deficiency does not alter the survival of mature granule neurons in the DG. (A) Smad3 mRNA expression was assessed by in situ hybridization on coronal sections of the adult hippocampus from wild-type mice. The arrow indicates Smad3 mRNA expression in cells located in the SGZ of the DG. The sense probe, used as a control, produced no staining. (B) Confocal images of Smad3/NeuN double labeling in the DG of Smad3+/+ and Smad3-/- mice highlighting the generally normal morphology in Smad3 null mice. Scale bar 100 μm. (C) Smad3 is expressed by mature granule neurons of the DG, both in the cytoplasm and nucleus. In SGZ cells, strong (arrowhead) and weak (arrow) Smad3 expression was detected. (D) Phospho-Smad3 is present in the cytoplasm and nucleus of mature granule neurons. (E) Smad3 null mice do not express Smad3 protein. Sections from three mice were analyzed and representative images are shown. Scale bar 10 μm. (F) In the DG, unbiased stereological methods were used to estimate the volume and the number of Nissl stained neurons or that of pyknotic nuclei in Smad3+/+ and Smad3-/- mice (n.s., student’s t- test, n = 6 mice per genotype).