Figure 2.

Ultrastuctural localization of the components of the nitric oxide system in the parvocellular part of the hypothalamic paraventricular nucleus (PVN) in mice. Electron micrographs illustrate the postsynaptic (A, C) and presynaptic (B, D) localization of nNOS-immunoreactivity in the parvocellular part of the PVN. The nNOS-immunoreactivity is labeled with highly electron dense gold–silver particles and observed in the proximity of both asymmetric (A, B) and symmetric (C, D) synapses. Soluble guanylyl-cyclase α1 subunit-immunoreactivity (sGCα1-IR) is present both in presynaptic axons (E, G) and in dendrites (F, H) in the paraventricular nucleus. sGCα1-immunoreactivity is recognized by the presence of the electron dense silver grains. sGCα1-immunoreactivity is present in axon varicosities forming both symmetric (E) and asymmetric type synapses (G). sGCα1-immunoreactivity is also seen in dendrites in the proximity of the postsynaptic density of both symmetric (F) and asymmetric (H) synapses. Arrows point to synapses. Abbreviations: a = axon; d = dendrite. Scale bars = 0.5 μm.