Figure 7.

Cbln1 is not required for axon extension to lumbar L1–L2. A, Experimental outline: Retrograde labeling with injection of CTB-555 at lumbar L1–L2 was performed in Cbln1 WT, Cbln1 Het, and Cbln1 null mice at P5, and the number of retrogradely labeled neurons throughout the rostro-caudal extent of medial sensorimotor cortex was analyzed at P7. B, There is no qualitative difference in the proportion of retrogradely labeled CSN in medial sensorimotor cortex at rostral, middle, or caudal levels between Cbln1 WT or Het ($n=3$) and Cbln1 null ($n=2$) mice. C–H, Representative rostral, middle, and caudal sections from a Cbln1 Het and a Cbln1 null mouse. Scale bars are 100 µm for insets and are 500 µm for all other images. I, Experimental outline. Anterograde labeling via biotinylated dextran amine (BDA) iontophoresis into caudomedial sensorimotor cortex was performed in Cbln1 Het and Cbln1 null mice at P28. The number of BDA-labeled axons at cervical C1–C2, thoracic T1–T2, and lumbar L1–L2 was counted at P35 for three axial sections per spinal level, and the average number of counts is plotted. J, There is no qualitative difference in the proportion of axons that reach thoracic T1–T2 or lumbar L1–L2 from cervical C1–C2 between Cbln1 Het and Cbln1 null mice. K–P, Representative axial sections from cervical C1–C2, thoracic T1–T2, and lumbar L1–L2 in Cbln1 Het and Cbln1 null mice. Scale bars are 100 µm.