Fig. 2.

Dark-field views of photomicrographs of some of the sections in Figure 1 with a more detailed illustration of IR-TH.A, TH fibers in the prefrontal cortex (Pfc) were primarily concentrated in the intermediate layer. B, C, The TH fiber distribution in the striatum was clearly patchy in appearance, and some of the fibers crossed the internal capsule (IC). C,D, A distinct network of fibers was observed in the internal and external segment of the globus pallidus (GPi, GPe). D, Within the hypothalamus TH cells and fibers were found in the periventricular, arcuate (Arc), and lateral hypothalamic nuclei; a distinct fiber bundle connects the lateral hypothalamus (LH) and the Arc.E, F, At day 70, TH cells and fibers within the ventral midbrain were densely intermingled; however, the various TH neuronal groups described in adult primates were also found at this stage in development (also see Fig. 4A).Cd, Caudate; IF, interfascicular nucleus;LV, lateral ventricle; Li, linear nucleus; OT, optic tract; Put, putamen;SN, substantia nigra; 3V, third ventricle; VTA, ventral tegemental area. Scale bar:A, B, 500 μm; C–F, 1.0 mm.