Figure 6.

Absence of monoamine-synthesizing enzymes in FI VENs and fork cells. Immunohistochemistry for the synthesizing enzymes for norepinephrine and dopamine (A; TH), serotonin (B; TPH, PH8), or histamine (C; HDC) in FI. Immunohistochemistry showed a pattern consistent with arriving TH axons, but no immunostaining was observed in VEN, fork cell, or neighboring pyramidal-shaped neuron somata. Higher magnification views are shown for VENs stained for TH (A’), PH8 (B’), and HDC (C’). Right panel shows positive controls for TH (SN, A”), PH8 (raphe nucleus, B”), and HDC (TMN, C”). Arrowheads indicate VENs; arrows indicate fork cells. Scale bars represent 50 μm (A, B, C) and 10 μm (A’, A”, B’, B”, C’, C”)