The Oxygen Receptor of the Teleost Gill?

Abstract

Sundin. L. Holmgren, S. & Nilsson. S. 1998. The oxygen receptor of the teleost gill?-Acra Zoologicu (Stockholm) 7 9 207-214.The gills of the Atlantic cod, Gadus morhua. were studied using immunohistochemical techniques. Primary antibodies directed against serotonin (5-hydroxytryptamine, 5-HT) and acetylated a-tubulin were used to visualise cells containing serotonin and nerve fibres, respectively. Three morphologically different 5-HT immunoreactive cell types were distinguished: (I) Neuroepithelial cells (NECs), which were abundant along the distal half of the efferent filamental arteries (EFAs), and particularly formed distinct clusters at the individual filamental tips, (11) bipolar neurones running next to the EFAs and (Ill) multipolar neurones innervating the proximal parts of the EFA. In addition, the study revealed a well-developed system of nerve fibres, some of which form plexuses in association with the NECs. A relatively rich innervation of the proximal part of the EFAs, in conjunction with the EFA sphincters was also observed. Delicate varicose terminals surround the bases of the efferent lamellar arterioles. The localisation of distinct clusters of NECs at the individual filamental tips and the close connection with nerve terminals suggests a function as external branchial oxygen receptors.

New developments on gill innervation: insights from a model vertebrate

“…those nerve fibres whose parent cell bodies are located within the gill filaments, and indicated the presence of three populations of intrinsic neurons. These observations confirmed previous reports of intrinsic neurons in teleosts Sundin et al, 1998a). The intrinsic innervation in the zebrafish gill is summarized in Fig.…”

“…2B,C). Previous studies have described nerve fibres of the gill filaments, including those identified as adrenergic, cholinergic, nitrergic and peptidergic (Donald, 1984;Donald, 1987;Dunel-Erb et al, 1982;Dunel-Erb et al, 1989;Bailly et al, 1989;Bailly et al, 1992;Sundin et al, 1998a;Zaccone et al, 2006). Only recently was innervation of the secondary lamellae characterized in zebrafish with zn-12 (Jonz and Nurse, 2003), and similar nerve fibres of the lamellae were identified in goldfish and catfish (Saltys et al, 2006;Zaccone et al, 2006).…”

Effect of natural confinement on the gill cell types and bony elements ofLebias fasciata(Teleostei, Cyprinodontidae): A morphological and immunohistochemical analysis

“…In fact, among the neuroendocrine cell elements, those positive to 5-HT prevail in the Ganzirri specimens, while in the Lesina specimens those positive to nNOS are predominant. They represent two rather distinct types of neuroepithelial cells that presumably have different anatomical distribution patterns (Burleson & Smatresk, 1990a, b;Burleson et al, 1992;Sundin et al, 1998). This also seems to be consistent with the data for the calcium-binding proteins, S-100 and Cb D28K (Fasulo et al, 1998), and the cytokeratin CK18 , which are considered markers of neuroendocrine cells.…”

Ammonia sensing by neuroepithelial cells and ventilatory responses to ammonia in rainbow trout

“…However, the sensors for the ventilatory response to hypoxia appear to be more diffuse and variable, sensing both external and internal gas levels (Daxboeck and Holeton, 1978). For example, in the catfish, the ventilatory response to hypoxia arises only from receptors confined to the gill arches (Burleson and Smatresk, 1990), but in many fish, total gill denervation fails to eliminate the hypoxic ventilatory response (Saunders and Sutterlin, 1971;Sundin et al, 1998) and the remaining receptors appear to occur at extrabranchial sites including the orobranchial cavity (Milsom et al, 2002).…”

“…Because the depolarizations induced by both hypoxia and hypercapnia are blocked by the presence of quinidine, a non-specific blocker of background K + channels, but not by several blockers of voltage-dependent K + channels, it has been proposed that these stimuli cause membrane depolarization by inhibiting background K + channels (Jonz et al, 2004;Qin et al, 2010). In turn, the elevation of [Ca 2+ ] i in NECs would lead to the subsequent release of neurotransmitter for the ventilatory modulation, with 5-HT being the prime candidate (Fritsche et al, 1992;Burleson and Milsom, 1995;Sundin et al, 1998;Jonz and Nurse, 2003;Coolidge et al, 2008). Catecholamines, ACh and ATP (co-stored with monoamines in vesicles) may also play important roles as likely neurotransmitters in NEC physiology (Burleson and Milsom, 1995;Coolidge et al, 2008;Nurse, 2010).…”