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.