Sema7A and plexinC1 expression in spinal cord, DRG and muscle. In situ hybridization for Sema7A and plexinC1 on consecutive coronal (A-H, K-N) and horizontal (I, J) sections of the spinal cord, dorsal root ganglion (DRG) and gastrocnemic muscle. (A, B) At E15, Sema7A and plexinC1 are detected in DRG neurons and throughout the spinal cord with highest expression in motor neurons (MN). (C, D) Panels C and D are higher magnifications of the ventral spinal cord shown in A and B, respectively. PlexinC1 is expressed in the floor plate (arrow in D). (E, F) Expression of Sema7A and plexinC1 in the E19 spinal cord and DRG. In the E19 DRG, most neurons express Sema7A but only few display plexinC1 signals. Both Sema7A and plexinC1 are expressed in motor neurons and in cells throughout the gray matter. (G, H) At P15, Sema7A and plexinC1 are expressed in motor neurons and throughout the gray matter (gm). No specific signals were detected in sections processed with corresponding sense controls. In addition, Sema7A is expressed in oligodendrocytes in the spinal cord white matter (arrows) (I) and plexinC1 labels ependymal cells lining the central canal (cc) (J). (K, L) In the adult, Sema7A and plexinC1 are expressed in adult small-(arrowhead) and large-diameter (arrow) DRG neurons. (M, N) Sema7A but not plexinC1 labels clusters of non-neuronal cells in the gastrocnemic muscle (arrowheads in M). The insert in M shows a higher magnification of a cluster of Sema7A-positive cells (indicated by an arrowhead). 7A, cc, central canal; Sema7A; C1, plexinC1; wm, white matter. Scale bar 150 μm (A, B), 90 μm (C, D), 225 μm (E, F), 540 μm (G, H), 125 μm (I, J), 220 μm (K, L), 500 μm (M, N), and 125 μm (insert in M).