Fig. 11.     Examples of nigral innervation of cholinergic neurons in the basal forebrain.  A:  Cholinergic neuron in the lateral part of the BST (boxed area) receiving afferent input from lateral VTA/medial SNC (case 93047).  B:  ChAT-immunoreactive cells in GP-SI area receiving input from the central part of SN (case 93049) with several cholinergic cells in box C.  C:  Enlarged view of two neurons in B. The dorsal neuron is shown at higher magnification in E, and the ventral neuron is enlarged in F.  D:  Enlarged view of the neuron from the boxed area in A. Note the color difference between the cholinergic neuron (brown) and the NiDAB-labeled bouton (black).  E,F:  Enlarged view of the boxed areas in C.  G:  This bouton establishes an asymmetrical synaptic contact (postsynaptic thickening indicated with filled arrows).  H, I:  Electron micrographs of labeled boutons, shown in E and F, respectively, establishing synapses (open arrows) with ChAT-positive proximal dendritic shaft (H) and cell body (I). Scale bars = 200 µm in A-C, 10 µm in D-F, 0.5 µm in G-I.