Figure 7. LR axons do not ramify locally and instead project to deeper layers and the corpus callosum. A. Schematic of the axonal ramifications of two LR neurons whose cell bodies are located within L2/3. Top left shows the location of the RSC within the slice. A slice with an anterior-posterior location of -1.82 mm was used in a P25 mouse. Layers and corpus callosum (CC) are demarcated by grey dashed lines, with the midline of the brain demarcated as a solid line. Scale bar represents 50 um. Dendrites are in black, and cell bodies/axons are in purple. Axons project clearly to deeper layers, with one entering the corpus callosum. Minimal axonal ramifications are observed in L2/3. Graphical insert is identical to that in Figure 2C with the three LR cells referenced here in larger purple dots, indicated by the arrows. All three LR cells cluster clearly within the LR cell group and separate from RS and FS cell groups. B. Biocytin fill used to create the schematic in A. Layers and the CC are demarcated by dashed lines, and the midline is a solid line. Arrows are placed periodically along the axon for visualization. Scale bar represents 50 um. C. Zoomed in view of the indicated box in A. Left shows a schematic of the axon projecting through L5/6 before entering and traveling within the CC. Right shows biocytin fill image. Arrows are placed periodically along the axon for visualization. Scale bar represents 50 um. D. Schematic of the third filled LR cell dendrites, cell body, and axon. A slice with an anterior-posterior location of -2.54 mm was used in a P24 mouse. Layers and corpus callosum are demarcated by grey dashed lines; a solid line indicates the midline. There are no axonal ramifications in the superficial layers, and the axon projects into deeper layers towards the corpus callosum. Scale bar represents 100 um.