Figure 5.

Retrograde Labeling of Caudally Projecting Neurons in Rat NPC Grafts

Rats received GFP-expressing NPC grafts into sites of C5 hemisection, and injections of Fluoro-Gold (FG) into the caudal host spinal cord 3.5 weeks later.

(A) GFP and NeuN immunolabeling reveal graft survival and integration into the lesion site, and the caudal FG injection site at C7 is also visible (arrowhead, Injec). Horizontal section with rostral on left and caudal on right.

(B) GFP and NeuN labeling show extension of large numbers of axons from graft into the caudal host spinal cord.

(C) Numerous axons extend caudal to the lesion site, and axons branch off from white matter (WM) into host gray matter (GM). Dashed lines indicate interface of white matter and gray matter.

(D) Low-magnification view demonstrates numerous cells in NPC graft that are retrogradely labeled with FG. Boxed areas are shown in (E).

(E) A cluster of FG⁺ cells in caudal half of graft. Fainter objects are likely cells in partial plane of section; inset shows background in rostral half of graft, which is devoid of FG background labeling.

(F) GFP/NeuN labeling reveals abundant NeuN-expressing cells within the GFP graft shown in (D) and (E).

(G) Two examples (arrows) of FG retrogradely labeled graft cells that co-localize with NeuN, suggesting neuronal identity of retrogradely labeled cells in graft.

Scale bars represent 1,000 μm (A), 210 μm (B), 40 μm (C), 400 μm (D and F), 30 μm (E), and 20 μm (G).