Smad3 promotes the proliferation of NPCs in the rostral DG. To analyze the proliferation of progenitor cells, mice received a daily injection of BrdU (100 mg/Kg) over 5 consecutive days and they were sacrificed 2 days after the final injection. (A) Smad3 deficiency did not affect the number of BrdU-ir cells in the SGZ, GCL or the hilus. (B-C) Representation of the SGZ along the rostro-caudal axis showed that Smad3-/- mice had more BrdU-ir cells in the initial rostral 500 μm but not in the middle and caudal regions of the SGZ (*, P ≤ 0.05, Student t-test, n = 5-7 mice per genotype). (D) Confocal images showing Smad3 expression in BrdU labeled proliferative cells of the SGZ. Scale bar 200 μm and 10 μm. (E-F) The endogenous marker of cell proliferation Ki-67 further confirmed the enhanced progenitor cell proliferation in the initial 750 μm rostral portion of the DG in Smad3-/- mice compared to that in Smad3+/+ mice (*, P ≤ 0.05, Student’s t-test, n = 5-6 mice per genotype). (G) The number of Nissl stained neurons in the rostral DG showed a non-statistical trend to increase in Smad3-/- mice in the rostral DG (P = 0.054, Student’s t-test, n = 6 mice per genotype).