LGN efferents contacting hypothalamic neuroendocrine and/or dopamine cells. Light micrographs of a hypothalamic section after visualization for PHA-L-containing LGN efferents (dark blue boutons; arrows), retrogradely labeled, fluorogold-containing neuroendocrine cells (dark blue cytoplasmic inclusions), and TH (homogeneousbrown cytoplasmic staining) in neuronal perikarya representing dopamine (DA)-producing cells. A, B, Dark blue boutons originating in the LGN in close proximity to an FG-containing perikaryon and dendritic process of the MPO and the periventricular area (Pe), respectively.C, D, Putative connections between IGL efferents (PHA-L-immunoreactive axon terminals; arrows) and non-neuroendocrine (FG-negative) dopamine cells in the anteroventral periventricular nucleus (AVPv) and Pe.E–G1, Retrogradely labeled (FG granules) dopamine cells (TH-immunoreactive) contacted by PHA-L-containing putative axon terminals (arrows) in the Pe (E), AVPv (F), and the lateral aspects of the arcuate nucleus (ARC) (G1). G2, Same cells as in G1 but at a different focus plane to enhance the visibility of FG-immunoreactive cytoplasmic inclusions. Scale bars, 10 μm.