Figure 1.

Time Course Analysis of the Dentate Gyrus Development in Trkb^Gad1-KO Mice and Controls

(A–F) (A, C, and E) and (B, D, and F) Representative images of hippocampal coronal sections from controls (BAC-Gad1-Cre^tg/+; Ai9^T/+) and mutants (Trkb^Gad1-KO; Ai9^T/+) at postnatal days 8 and 21 and 2 months (P8, P21, and 2M), respectively, highlighting the forming dentate gyrus (DG) by tdTomato (red) endogenous fluorescence superimposed to DAPI staining (blue). Insets show higher magnification of the DG at all respective ages. Note the endogenous tdTomato fluorescence highlighting the distribution of mossy fiber bundles in control and Trkb^Gad1-KO mice, namely the infrapyramidal mossy fiber (IPB) and the suprapyramidal mossy fiber (SPB) bundles, as well as the mossy fiber (MF) terminals targeting the hippocampal CA3 region.

(G–N) (G–J) and (K–N) Representative images of hippocampal coronal sections from controls (BAC-Gad1-Cre^tg/+; Ai9^T/+) and mutants Trkb^Gad1-KO; Ai9^T/+ at P21 and 2M, respectively, highlighting Calbindin immunostaining in mature dentate cells in the granule cell layer (GCL) and mossy fibers (MFs) targeting the CA3 region.

(O and P) Representative images and respective insets showing caspase 3 immunofluorescence-stained (green) cells in the subgranular zone (SGZ) of both control (O) and mutant (P) mice indicated by a white arrow.

Scale bars: 100 μm in (A and B) and 50 μm in respective insets; 200 μm in (C–F) and 100 μm in respective insets; 200 μm in (G, I, K, and M); 50 μm in (Η, J, L, and N); and 25 μm in (O and P) and respective insets. See also Figure S1.