Vagal paraganglia of the rat

Abstract

Paraganglia are associated with every branch of the rat vagus nerve except the pharyngeal branch. Some of the paraganglia closely resemble the glomus caroticum, whereas others appear like small, intensely fluorescent (SIF) cells of autonomic ganglia. The paraganglionic cells of SIF cell-like bodies (SLB) store catecholamines (the most abundant is probably noradrenaline) and in some cases neurotensin. The innervation pattern of SLB is variable and their physiological role remains unclear. Paraganglionic cells of glomus-like bodies (GLB) predominantly store dopamine and probably also to a lesser extent noradrenaline. These putative chemoreceptor organs receive sensory innervation from nodose ganglion neurons as revealed by degeneration experiments and by anterograde neuronal tracing. Substance P- and calcitonin gene-related peptide-immunoreactive fibres seen in the region of vascular entry into the GLB may account for some of these sensory fibres, but the peptide/classical transmitter stored in sensory terminals synapsing on paraganglionic cells is unknown. Ultrastructural immunocytochemistry revealed vasoactive intestinal polypeptide (VIP)-immunoreactive fibres lying in the interstitial space between paraganglionic cells and large capillaries. These fibres may originate from VIP-immunoreactive neurons, being frequently attached to GLB. The major difference between GLB and the glomus caroticum concerns their blood supply and related innervation: Arteries and arterioles do not penetrate into GLB and, accordingly, noradrenaline- and neuropeptide Y-containing nerve fibres are lacking within GLB. This peculiar arrangement of paraganglionic parenchyma and arterial blood supply may be one of the reasons for the different physiological properties of vagal and carotid arterial chemoreceptors.

Pulmonary intraepithelial vagal nodose afferent nerve terminals are confined to neuroepithelial bodies: an anterograde tracing and confocal microscopy study in adult rats

“…Considering all the above-mentioned arguments, it seems most plausible at the moment to assume that not all NEBs in adult rat lungs receive innervation from the vagal sensory nodose ganglion. Similarly, not all vagal paraganglia seem to receive innervation by vagal nodose afferents (Kummer and Neuhuber 1989;Berthoud et al 1995b). Although no degeneration of NEB innervation has been observed at the electron-microscopic level after supranodosal vagotomy in other species (Lauweryns et al 1985), our results do not rule out with certainty the innervation of rat pulmonary NEBs by so far unidentified vagal sensory nerve endings originating in the jugular ganglion.…”

Innervation of laryngeal nerve paraganglia: An anterograde tracing and immunohistochemical study in the rat

“…This observation also indicates that nerve terminals in the paraganglia, namely those exhibiting CGRP-LI, originate in the vagal ganglia. In line with our findings after vagotomy are the observations that the nerve endings that are in close contact with the type I cells in the laryngeal nerve paraganglia (McDonald and Mitchell, 1975; Carlsoo et al, 1983) degenerate after infranodose vagotomy but are unaffected by supranodose vagotomy (Kummer and Neuhuber, 1989).Injection of WGA-HRP in the SCG did not label nerve fibers either in the laryngeal nerves or in the paraganglia. Thus, the SCG does not seem to innervate the paraganglia.…”

The distribution of presumptive thoracic paraganglionic tissue in the common marmoset (Callithrix jacchus)

“…An ultrastructural study could probably demonstrate cytological characteristics shared with type 1 cells, but would be very difficult to carry out in view of the protean distribution of these cells. In the mediastina of non-primate animals collections of small clear cells have also been observed along the course of the left vagus nerve and described as being similar to small intensely fluorescent cells that are found in autonomic ganglia (19). The small clear cells we have observed are slightly larger than small intensely fluorescent cells.…”