Figure 1.

Cell-type-specific expression of GCaMP3 in OBs and distinct OSN axon trajectories in IPA-responsive glomeruli. A1–A4, Confocal images of OBs in Cre-dependent GCaMP3 reporter mice crossed with OMP-Cre (A1), Gad2-Cre (A2), DAT-Cre (A3), and Pcdh21-Cre (A4) mice. Magnified views of the dashed squares are shown in the insets in A2, A3. GL, EPL, MCL, and GCL indicate GL, external plexiform layer, MCL, and GCL, respectively. B, Process for the DiI labeling of OSN axons. B1, Resting fluorescence of GCaMP3 in the dorsal OB of OMP-Cre mouse. B2, IPA (0.02%)-responsive homologous glomeruli were observed by calcium imaging [color scale indicates ΔF/F₀ (%) of GCaMP3 signal]. B3, Brightfield image after DiI implantation. B4, DiI fluorescence 30 min after DiI implantation. B5, DiI fluorescence 8 h after DiI implantation. The locations of IPA-responsive glomeruli are indicated by the white dotted circles. C, Two-photon microscopy image of DiI-labeled glomeruli and OSN axons 2 d after DiI implantation. D, Magnified image of area denoted by orange dotted square in C associated with lateral glomerulus. E, Magnified image of area denoted by yellow dotted square in C associated with medial glomerulus. Two-photon microscopy images of OSN axons that transverse the lateral and medial surface of OB; orange and yellow dotted ellipses (in C–E) represent major axonal projections from lateral and medial glomeruli. F, Two-photon microscopy images of areas of lateral/medial border denoted by blue dotted square in C. Red asterisks indicate axon termination in several glomeruli in which the labeled OSNs probably passed through the surface of the DiI-implanted glomeruli. Some minor axons which did not show clear axon terminations in a glomerulus were observed in area 2 in this case. Ant., anterior. Lat., lateral. Scale bars: 100 μm (A), 200 μm (B, C), 50 μm (D, E), and 100 μm (F).