Epithelial gill cells in the armored catfish, Hypostomus cf. plecostomus (Loricariidae)

Abstract

Epithelial gill cell morphology and distribution were investigated in the armored catfish, Hypostomus cf. plecostomus, which lives in soft ion-poor Brazilian freshwaters. Pavement cells are the most abundant type of cell on both filament and lamellar epithelia and there are a great number of mucous and chloride cells between them. Mucous cells are almost covered by adjacent pavement cells and have large packed granules showing electrondense differences. No mucous cells were found on the lamellar epithelium. Chloride cell were distributed throughout both epithelia and usually have large apical surface facing the external medium and may exhibit short and sparsely distributed microvilli. The presence of chloride cells on the lamellar epithelium may be an adaptation to low ion concentrations in the water, allowing for improved ion-transport capacity of the gill. The large size of these cells increases the water-blood barrier and may affect the transference of respiratory gases. However, the negative effect on the respiratory process may be minimized by this species' ability to resort to atmospheric air to fulfill its oxygen requirements.Key words: gills, epithelium, teleost, loricariid, Hypostomus cf. plecostomus. RESUMOEpitélio branquial de cascudo, Hypostomus cf. plecostomus (Loricariidae)

Alterações do epitélio branquial e das lamelas de tilápias (Oreochromis niloticus) causadas por mudanças do ambiente aquático em tanques de cultivo intensivo

“…E esta forma de proteção pode ser avaliada através do número das células produtoras das glicoproteínas (mucinas) que compõem este muco, assim como, pela análise das características químicas de seus componentes (Fernandes & Perna-Martins 2001, Breseguelo et al 2004. Neste sentido, calculou-se a densidade populacional de células mucosas em todo o filamento branquial, e observou-se que houve aumento expressivo do número de células produtoras de mucinas neutras nos animais do T 3 em relação ao T 2 e T 1 (p<0,05), contudo não houve diferença no número destas células nos animais do T 4 (p>0,05).…”

Response of mucous cells of the gills of traíra (Hoplias malabaricus) and jeju (Hoplerythrinus unitaeniatus) (Teleostei: Erythrinidae) to hypo- and hyper-osmotic ion stress

“…The lamellar or respiratory epithelium has two cell layers which consist of pavement cells in the outermost layer and undifferentiated cells in the innermost one. Several studies on the teleost gill epithelium have emphasized the pavement cells (PVCs) of the lamellar epithelium which are directly related to gas exchange and the chloride cells (CCs) which are related to the ion regulation as well as the changes of these cells in response to the internal and/or external ionic or acid-base environment (Munshi, 1964;Perry & Laurent, 1993;Goss et al, 1994;Moron & Fernandes, 1996;Fernandes & Perna-Martins, 2001;Moron et al, 2003;Sakuragui et al, 2003). Mucous cells (MCs) in the epithelial lining of the gill filament and their responses to environment have been intensively studied by Munshi, Hughes and their associates (Hughes & Munshi, 1979;Singh & Munshi, 1996;Parashar & Banerjee, 1999a, 1999b, 1999cChandra & Banerjee, 2003Diaz et al, 2004Diaz et al, , 2005Banerjee, 2007).…”

“…Most of the Brazilian freshwater is soft and ion-poor (Esteves, 1998) and fish inhabiting such environment exhibit great diversity in the distribution and density of some gill cells as a compensatory adjustments to maintain the gill functions (Fernandes & Perna-Martins, 2001Moron et al, 2003). For example, the traíra, Hoplias malabaricus, a water-breathing fish, and the jeju, Hoplerythrinus unitaeniatus, a facultative air-breathing fish, living in the same environment show different chloride cell density in the filament and lamellar epithelia of gills and also in the response to different ion concentration in water (Fernandes & Moron, 1996;Moron & Fernandes, 1996;Moron et al, 2003).…”

Chloride cell responses to ion challenge in two tropical freshwater fish, the erythrinids Hoplias Malabaricus and Hoplerythrinus Unitaeniatus

“…A great diversity of distribution and CC density has been found among Brazilian species living in this type of environment (Mazon et al, '95;Moron and Fernandes, '96;Fernandes et al, '98;Fernandes and Perna-Martins, 2001). Among these species, two ecologically distinct erythrinids, Hoplias malabaricus (Bloch)Fan exclusively water-breathing species, and Hoplerythrinus unitaeniatus (Spix)-Fa facultative air-breathing fish, display a great diversity of CC distribution throughout the filament and lamella and of CC apical surface area.…”