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Background: The distribution of neural structures in human nasal vasculature is still not completely understood. To date, immunocytochemical and histochemical studies of the innervation pattern and neurotransmitter distribution have only been performed using light microscopy. The aim of this study was to verify these results by electron microscopy and to obtain new knowledge of the innervation of the individual vessel types. The target was to determine the role of the different vessels in the swelling mechanism in human nasal mucosa., Material and Methods: Specimens were prefixed in glutaraldehyde and postfixed in osmium tetroxide. After dehydration they were embedded in araldite. Ultrathin sections were cut, contrasted with uranylacetate and lead citrate, and studied under EM., Results: Nasal vasculature is controlled by a dense innervation. Amyelinated longitudinal nerve bundles and smaller axon conglomerates are detected in the arterial adventitia. Capacitance vessels (veins) in general show few nerve structures, which, in contrast to arteries, are also located between the smooth muscle cells. Cushion veins, however, reveal a stronger innervation pattern especially in their muscular swelling. In contrast to smaller arterioles, no axons can de demonstrated in capillaries., Conclusion: The density of innervation in arteries and cushion veins seems to indicate that these vessel types are the central neural control point for the swelling mechanism in human nasal mucosa. Capillary function, however, does not seem to be directly influenced by the autonomic nervous system.

Nitric oxide (NO) is suggested as an important mediator for the regulation of biological processes. In the present study we tried to determine histochemically and immunohistochemically the localization and distribution of the constitutive NO-synthase Isoforms (bNOS and eNOS) of 14 normal non-obstructive and 12 hyperplastic obstructive human prostates. Differentiated nitrinergic innervation was shown for the prostate glands, fibromuscular stroma and blood vessels by NADPH-diaphorase staining and immunohistochemically with specific NOS antibodies. In the specimens with benign prostatic hyperplasia nitrinergic innervation seems to be distinctly reduced. The vascular distribution of NOS provides evidence for segmental differentiation of NO-mediated vascular regulation. The NADPH-diaphorase reaction was not confirmed immunohistochemically by the specific NOS antibody in the glandular epithelium. The distribution of NO synthase shows the importance of nitric oxide in the regulation of smooth muscle tone, blood flow and secretory function in the normal and hyperplastic human prostate.