Figure 7 - Fluo-NT-labeled neuron in the ventral tegmental area of an adult rat brain. Sections from the ventral midbrain were superfused during 3 min with 20 nM fluo-NT at 37oC, rinsed for 10 min in buffer, fixed with 4% paraformaldehyde and optically sectioned. Internalized ligand molecules are evident within endosome-like organelles throughout the perikaryon sparing the nucleus (n). Labeled endosomes are also evident within the proximal processes of the cell (arrow). No labeling was apparent when the incubation was carried out at 4oC or at 37oC in the presence of an excess of nonfluorescent NT. Scale bar: 15 Ám.