Fine structure of the branchial epithelium in the teleost Oreochromis niloticus

Abstract

We have studied the gill epithelium of Oreochromis niloticus using transmission electron microscopy with the particular interested relationship between cell morphology and osmotic, immunoregulatory, or other non-regulatory functions of the gill. Pavement cells covered the filament epithelium and lamellae of gills, with filament pavement cells showing distinct features from lamellar pavement cells. The superficial layer of the filament epithelium was formed by osmoregulatory elements, the columnar mitochondria-rich, mucous and support cells, as well as by their precursors. Light mitochondria-rich cells were located next to lamellae. They exhibited an apical crypt with microvilli and horizontal small dense rod-like vesicles, sealed by tight junctions to pavement cells. Dark mitochondria-rich cells had long dense rod-like vesicles and a small apical opening sealed by tight junctions to pavement cells. The deep layer of the filament epithelium was formed by a network of undifferentiated cells, containing neuroepithelial and myoepithelial cells, macrophage and eosinophil-like cells and their precursors, as well as precursors of mucous cells. The lateral-basal surface was coated by myoepithelial cells and a basal lamina. The lamellar blood lacunae was lined by pillar cells and surrounded by a basal lamina and pericytes. The data presented here support the existence of two distinct types of pavement cells, mitochondria-rich cells, and mitochondria-rich cells precursors, a structural role for support cells, a common origin for pavement cells and support cells, a paracrine function for neuroepithelial cells in the superficial layer, and the control of the lamellar capillary base by endocrine and contractile cells. Data further suggest that the filament superficial layer is involved in gill osmoregulation, that may interact, through pale mitochondria-rich cells, with the deep layer and lamellae, whereas the deep layer, through immune and neuroendocrine systems, acts in the regeneration and defense of the tissue.

Morphological Studies on the Gills of Puffer Fish (Lagocephalus sceleratus, Gmelin, 1789)

“…Interestingly, the present study showed presence of tertiary lamellae, originated from some secondary lamellae as noted by (Hughes & Mittal, 1980;Arpigny et al, 2012) and expected to increase the respiratory surface area within the gills The morphology and distribution of the different cell types of the gill epithelium of teleosts have been intensively investigated in order to understand and recognize the integration of several of their functions (Wilson & Laurent, 2002;Díaz et al, 2010;Monteiro et al, 2010). Our histological finding investigated that filaments are covered by primary epithelial layer with many mucous cells interspersed in it.…”

Surface Ultrastructure of the Gills of Odontesthes bonariensis (Valenciennes, 1835)(Teleostei: Atheriniformes) from a Temperate Shallow Lake

“…The branchial filament possesses a multilayered epithelium. The superficial region of the filament epithelium mainly contains chloride and mucous cells, externally covered by pavement cells that, in addition to their role in gas exchange, are presumed to be involved in ionoregulatory mechanisms (Evans et al, 2005;Díaz et al, 2009;Monteiro et al, 2010). Lamellae, the predominant part of the arterio-arterial system, are covered by a thin epithelium.…”

“…The modifications of the ultrastructural surface of gills can reflect the fish health and the physiological status (Fernandes & Perna-Martins, 2002). Hence, the knowledge of the normal structural features of gills contributes to better understand the diverse physiological processes that occur in the organ (Carmona et al, 2004;Monteiro et al, 2010). Moreover, the gills are sensitive indicators of environmental stress, including exposure to harmful compounds present in aquatic ecosystems as a result of human activities (Vigliano et al, 2006).…”

Paracellular pathway remodeling enhances sodium secretion by teleost fish in hypersaline environments

“…, and form a localized cation-permeable pathway (Sardet et al, 1979;Scheffey et al, 1983) in an epithelium of pavement cells that are connected by deep, relatively impermeable tight junctions (Monteiro et al, 2010;Sardet et al, 1979). These permeable junctions balance the anion current emanating from the ionocyte and together comprise the total measurable epithelial conductance, as detected by vibrating probe experiments (Foskett and Machen, 1985).…”