Electron microscopic analysis of ecto-nucleoside triphosphate diphosphohydrolase 3-(NTPDase3) immunoreactive hypothalamic profiles. A: Grainy cytoplasmic immunoreactivity (inset, black arrow) may result partly from NTPDase3-IR material linked to ribosomes (black arrows). Scale bar: 400 nm. B: Light microscopic studies showed NTPDase3-immunoreactive dots (b1 inset, black arrow) outlining the boundaries of immunoreactive cells. Scale: 50 μm. Correlated electron microscopic examination showed that immunoreactive dots shown on b1 represent plasma membrane-linked aggregates with Nickel-DAB-labeling on the extracellular side (b1'; Arrowhead points to the plasma membrane. Upper white arrow indicates cytoplasmic immunopositive material; Lower white arrow points to a plasma membrane-bound immunoreactive material. Scale bar: 100 nm.) ctpl: cytoplasm. C1: Representative image of an NTPDase3-immunoreactive dendrite (d). Scale bar: 0.5 μm. C2: Representative image of a myelinated axon (ma) containing NTPDase3-immunoreactive mitochondria (arrow). Scale bar represents 1 μm. D1: NTPDase3-immunoreactive material in the mitochondrial (m) matrix (arrows) or linked to the inner mitochondrial membrane in a dendrite (d) Scale: 200 nm. D2: NTPDase3-immunoreactive mitochondria in a dendritic (d) spine (black arrows) near an asymmetric synapse and in an unmyelinated axon (a) segment (white arrowheads). Scale: 400 nm.