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1.
Abstract. Brown trout, Salmo trittta L., from two fish farms, situated within acid-susceptible areas in Sweden, were studied with respect to aluminium accumulation and gill pathology. The total aluminium concentrations, after liming of the water in both farms, were between 200 and 300μg/1 at sampling. Brown trout from a third farm in a non-acidified area (total aluminium concentration of water 35μg/1 were included as a control. The aluminium concentrations in gills from farmed brown trout in acidified areas were approximately 20μg/g and 90μg/g wet weight respectively compared with approximately 2μg/g wet weight in control brown trout gills. Light- and electron microscopic examination disclosed two major types of gill lesions characterized by chloride cell hyperplasia in the secondary lamellar epithelium and enlargement of the intercellular spaces in the secondary lamellar epithelium. The difference in the aluminium speciation and accumulation may explain the difference in the gill pathology of farmed fish from acidified areas. The chloride cell hyperplasia together with a relatively low aluminium accumulation is considered to reflect a long-term exposure effect. 相似文献
2.
T. K. Banerjee 《Fish physiology and biochemistry》2007,33(4):441-454
Air-breathing fishes have evolved bimodal respiratory mechanisms for exploitation of water (through gills and highly vascularized
skin) as well as atmospheric air (through aerial respiratory organs, ABO). Mucous cells in these respiratory organs of variously
stressed fishes exhibit periodic fluctuations in their density and staining properties. The main types of damage in the gills
include congestion of blood capillaries (BLCs), periodic lifting and sloughing of respiratory epithelia of the secondary lamellae
causing haemorrhage, extensive fusion of secondary lamellae and hyperplasia of the respiratory epithelia due to uncontrolled
regeneration leading to asphyxiation, altered excretion, and death of the fish. Haemolysis has also been observed following
lead exposure. The damage in the ABO of Heteropneustes fossilis includes sloughing of the epithelial cells, leading to haemorrhage causing decreased red blood corpuscles density and degeneration
of the secondary gill lamellae with reduced respiratory area. Subsequent hyperplasia of the respiratory epithelia and fusion
of gill lamellae increase the respiratory barrier distance. The BLCs often bulge out and protrude into the lumen, bringing
blood nearer to air. The ladder-like pillar cell (PLC)-BLC components of the gill lamellae frequently collapse. Damage to
the ABO of Channa striata is less severe. Often haemorrhaging due to bursting of extensively stretched BLCs causes aerial respiratory failure. Chloride
cells of the ABOs also show hyperplasia. While the highly mucogenic epidermis of C. striata shows less damage, the epidermis of Clarias batrachus and H. fossilis shows severe wear and tear, sloughing, and haemorrhage. Side-by-side regeneration continues, causing altered histomorphology
of the epidermis. The different gland cells also show periodic fluctuations in their density and staining. The dermis also
shows severe damage with loosening of their connective tissue fibres. These fibres give stronger reactions for sulfated mucin
that not only retain additional water molecules for continuance of skin breathing, but also bind the toxic ambient pollutants. 相似文献
3.
急性氨氮胁迫及毒后恢复对团头鲂幼鱼鳃、肝和肾组织结构的影响 总被引：7，自引：3，他引：4
为进一步了解氨氮对团头鲂幼鱼的毒性毒理影响,以体质量为(14.27±0.01)g的团头鲂幼鱼为研究对象,研究了氨氮胁迫对其鳃、肝、肾组织结构的影响。实验首先进行96h的氨氮胁迫,得出96h LC50,在此基础上,设置对照组(0.472 mg/L)和实验组(25 mg/L)两个氨氮浓度处理组,进行0、6、12、24、48h的氨氮胁迫,取样后剩余团头鲂幼鱼移入曝气自来水进行96h的毒后恢复实验。结果表明：96h LC50为56.492 mg/L;三种组织观察表明,氨氮胁迫6h,鳃丝毛细血管扩张,上皮组织增生;肝细胞肿胀,细胞核肿大,肝细胞空泡化;肾小球萎缩,肾小囊腔膨大,肾小管管腔缩小;胁迫12h,泌氯细胞增生,呼吸上皮细胞出现部分脱落;肝细胞水样变性、血窦扩张、细胞轮廓模糊,形成点状病灶;肾小管上皮细胞肿大、水样变性、浊肿;胁迫24h,鳃小片融合、变短,呼吸上皮细胞大面积脱落;肝细胞水样变性、血窦扩张严重,形成局部病灶;肾组织淋巴细胞浸润严重,充血,肾小球坏死,肾小管坏死;胁迫48h,鳃小片卷曲,上皮细胞部分脱落;肝细胞部分溶解、血窦扩张,形成点状病灶;肾小管上皮细胞坏死,肾小球坏死;96h恢复后,泌氯细胞和上皮组织增生严重;肝组织大面积细胞核肿大,血窦扩张;肾组织淋巴细胞浸润严重,肾小管坏死,肾小球坏死。实验表明,不同的器官之间病症的损伤程度是不同的,肝组织的损伤最严重,然后依次是鳃和肾。随着胁迫时间延长,鳃、肝和肾组织受到的损害增加,同时鱼体也产生防御反应,但96h的恢复期不足以让团头鲂幼鱼在胁迫中完全恢复,而恢复能力最差的是肾组织。 相似文献
4.
Twelve tanks of juvenile rainbow trout, Oncorhynchus mykiss (Walbaum), were treated twice weekly for an 11- week period with a one-hour static bath of chloramine-T (10 mg l–1 ). The morphometric indices of gill damage and the histochemical characteristics of gill mucous cells of fish from treated and paired untreated tanks were compared. The use pattern of chloramine-T in this study evoked a slight increase in mean lamellar width, but it did not induce a greater degree of lamellar oedema, lamellar fusion, tissue infiltration, epithelial hyperplasia, chloride cell metaplasia or thrombosis of pillar channels in treated fish. Treatment caused a trend towards an increased number of mucous cells on lamellae, associated with a significant shift from neutral mucin to acid mucin production based on histochemical characteristics. 相似文献
5.
Juvenile Epinephelus coioides were exposed to three nominal concentrations (8, 32, 128 mg wet sediments L?1) of suspended sediments (SS) from Port Shelter (PS), Mirs Bay (MB) and Victoria Harbour (VH) for 10 and 30 days using semi‐static system. Sediments from VH contained higher concentrations of Cu and polycyclic aromatic hydrocarbons (PAHs) than sediments from PS and MB. Gill damages including lamellar blood sinus dilation and vascular congestion were prevalent after just 10 days of exposure to SS. Fish exposed to SS at the highest concentration of 128 mg L?1 showed higher incidence of lamellar aneurism. Hyperplasia in the base of lamellae was recorded in fish that had been exposed to contaminated SS from VH. Significant increases in the density of chloride cells and mucous cells were found on the gills of fish that had been exposed to 128 mg L?1 of SS from PS. Clogging of gills by SS produced hypoxic‐like responses in fish. Polluted sediments from VH produced addictive or synergistic effects between SS and chemical contaminants on fish. 相似文献
6.
V. E. Ostland P. J. Byrne J. S. Lumsden D. D. MacPhee J. A. Derksen M. Haulena K. Skar E. Myhr H. W. Ferguson 《Journal of fish diseases》1999,22(5):351-358
An unusual form of bacterial gill disease (BGD) was identified which affected five species of cultured salmonids from Canada (i.e. rainbow trout, chinook salmon and Atlantic salmon), Norway (i.e. brown trout) and Chile (i.e. coho salmon). All outbreaks occurred at low water temperatures (< 10 °C) and with clinical presentations distinct from classical BGD, which is caused by Flavobacterium branchiophilum. In contrast to classical BGD, fish did not show marked respiratory distress with flaring of the opercula, the animals did not orientate at the surface of the water column near inflow water or at the margins of the tanks, and the feed response of the fish was varied. While mortality was increased, it was not precipitous as in classical BGD. Eight outbreaks were examined in greater detail using histopathology, scanning electron microscopy, bacteriology and immunohistochemistry. Large numbers of small bacterial rods were seen adhering to the lamellar epithelium of affected gills from all outbreaks. Histologically, the lamellar epithelium appeared swollen, often with evidence of single cell degeneration and exfoliation. In more severe instances, the formation of lamellar synechiae was seen, usually associated with sequestration of bacteria between fused lamellae. By contrast with typical BGD, overt epithelial hyperplasia, lamellar fusion and filamental clubbing were not common sequelae to infection; instead, the end result was shortened and somewhat stubby lamellae covered with swollen epithelial cells. The predominant bacterium recovered from affected gills was a small, Gram-negative, motile, fluorescent pigment-producing rod that shared phenotypic characteristics with Pseudomonas fluorescens. Polyclonal antisera prepared against three representative isolates indicated a weak antigenic similarity among them. Immunohistochemistry corroborated this finding, in that the antisera reacted strongly with gill sections containing the homologous bacteria, but not against morphologically similar bacteria in heterologous sections. A Gram-negative, yellow pigmented bacterium (YPB), identified as Flavobacterium psychrophilum, was also recovered, but only from the gills in the Ontario outbreaks. Antiserum prepared against this YPB indicated an antigenic similarity among isolates recovered from the Ontario outbreaks, but immunohistochemistry failed to recognize antigenically related bacteria on the gills of fish from the other outbreaks. Based on the unusual clinical presentation and the histopathological appearance of the gills, in conjunction with the absence of filamentous bacteria associated with and recovered from affected gills, the present authors have called this condition ‘atypical bacterial gill disease’ or ABGD. 相似文献
7.
D. J. SPEARE H. W. FERGUSON F. W. M. BEAMISH J. A. YAGER S. YAMASHIRO 《Journal of fish diseases》1991,14(1):21-32
Abstract. This study examines the sequential pattern of bacterial colonization and the sequential development of branchial lesions during typical outbreaks of bacterial gill disease (BGD) among four groups of commercially reared rainbow trout fingerlings, Oncorhynchus mykiss (Richardson). During a 5-month monitoring regime, prior to the onset of natural outbreaks of BGD, gill morphology of examined fish remained unaltered. Bacterial colonization of the gills was immediately preceded by several gill changes which were widely present in fish from all groups under study. These changes, which were detectable at the ultrastructural level only, included cytoplasmic blistering and degeneration of the microridges of the superficial filament epithelium, in addition to slight topographical irregularity of the filament tips suggestive of mild hyperplasia. Bacterial colonization began at these altered filament tips before spreading to more proximal regions of the filament and adjacent lamellar surfaces. Explosive increases in proportional morbidity and mortality coincided with the development of the following gill lesions: extensive bacterial colonization of lamellar surfaces, lamellar epithelial hydropic degeneration and necrosis, and lamellar oedema. In contrast, gill lesions such as lamellar fusion, epithelial hyperplasia and various metaplastic responses were detected later either as subacute (3–5 days) or chronic (7–14 days) changes. The role of epithelial necrosis as an important event during BGD is discussed as a possible mechanism leading to the development of sub-acute and chronic gill lesions. 相似文献
8.
Unscrupulous inclusion of melamine in fish feeds can be harmful to fish and may be hazardous to human health. An eight‐week feeding trial examined the effects of melamine (inclusion levels; 5–30 g kg?1 feed) on the growth performance, feed efficiency, histopathological changes and melamine residues in sex‐reversed red tilapia, Oreochromis niloticus (L.) × O.mossambicus (Peters). Fish which received melamine‐containing feeds grew less, utilized feeds less efficiently and performed poorly, besides exhibiting defects such as fin erosion, anorexia, sluggish swimming behaviour, paling/darkening of skin and low survival. Melamine concentration in the fish reflected its inclusion level in the feeds, and the content was higher in the viscera than in the fish fillet or whole fish. Histopathological alterations were evident in the kidney, liver and gills of fish subjected to melamine treatment – the severity of lesions corresponded to its dosage. Enlargement of renal tubules was observed in the kidney of fish fed with ≥10 g melamine kg?1 feed, although, crystals were not deposited. Fish subjected to melamine insult had more prominent lesions in liver than in kidney. Toxic effects on the gills manifested as epithelial hyperplasia of the primary and secondary lamellae. The anomalies were severe at higher intake levels of melamine. 相似文献
9.
Gill respiratory surface area and oxygen consumption during aquatic respiration were measured in the facultative air-breathing loricariid fish,Hypostomus plecostomus. The fish did not surface to breathe atmospheric air in normoxic water; air-breathing was evoked by environmental hypoxia (water oxygen tension=35±2, mmHg) and did not show size-related threshold differences for air breathing.During gradual hypoxia, without access to atmospheric, air,H. plecostomus was found to be an oxyregulator and showed a reduced range of water oxygen tension in which the oxygen consumption remained constant in smaller fish. The critical oxygen tensions were 55 and 33 mmHg at 25°C for fish of 14–30 g and 31–80g body weight, respectively.The gill respiratory surface area (total lamellae area) is reduced, however, the lamellar frequency per mm of gill filament is high which facilitates the gas exchange. Moreover, the increase of gill respiratory surface area (b=0.666) is higher than the increase in routine VO2 (b=0.338) showing a positive relationship between the gill respiratory surface area /VO2 ratio and body mass (b=0.328); this indicates that the fish have greater gill respiratory surface area per unit of routine VO2 as they grow. 相似文献
10.
Abstract. The tidewater silverside, Menidia beryllina, and the hogchoker, Trinectes maculatus, were exposed to south Louisiana whole crude oil (WCO) and its water-soluble fractions (WSF) to assess histopathological effects on their gills, olfactory organ, and liver. Both fishes were exposed to 5 mg WCO/1, 100 mg WCO/1, 5% WSF, and 50% WSF. Additionally, M. beryllina was exposed to 100 mg WCO/1 with 20 ppm Terramycin® to study possible complications caused by bacteria. Exposure of M. beryllina lasted 21-30 days, whereas experiments using T. maculatus continued for 38-60 days. Pathological changes in M. beryllina appeared by day 7 and became severe as experiments progressed to day 30. Histological alterations in the silverside included epithelial hyperplasia and fusion of gill lamellae, separation of respiratory epithelium from underlying tissue, hyperplasia of sustentacular cells of olfactory lamellae, necrosis of both neurosensory and sustentacular epithelium, extensive lipid vacuolation in hepatocytes, and atrophy and necrosis of intrahepatic exocrine pancreatic nodules. Of the tissues examined, the pancreas served as the most specific pathological indicator of oil pollution. In T. maculatus, hepatocytes of exposed individuals did not become vacuolated, and, except for gills exposed to 100 mg WCO/1, response by gills in the other three tests remained limited to slight hyperplasia. Olfactory mucosa of the hogchoker exhibited severe necrosis of both neurosensory and sustentacular cells in the high concentrations of oil, but no damage in low concentrations. The intrahepatic pancreas of fish exposed to all test-concentrations atrophied and became necrotic by the end of experiments. Limited studies using both Terramycin and a combination of Terramycin and WCO indicated lack of bacterial involvement in tissue damage in oil-exposed silverside, but the size of hepatic nuclei increased in the Terramycin-control fish, and the shape of lipid vacuoles appeared unusual subsequent to exposure to the combination. Menidia beryllina became hyperactive and refrained from feeding for up to 6 h after the initial administration of oil, whereas T. maculatus apparently never fed, and it exhibited hyperactivity after all exchanges of sea water and fresh oil. Deaths appeared to correspond both to degree of pathological damage and to exposure-concentrations. Partial to complete recovery was observed in gills, olfactory organ, and pancreas of M. beryllina exposed to WCO or WSF for 20 days and then maintained in oil-free sea water for 17 days. 相似文献
11.
12.
Abstract. Nodular gill disease characterized by severe multifocal epithelial hyperplasia was diagnosed in a group of rainbow trout, Salmo gairdneri Richardson, fingerlings. Gills of a large proportion of fish transferred from the affected tank to smaller aquaria showed a marked decrease in severity of the lesions after 2 months. Repair of hyperplastic lesions may occur in various forms of proliferative gill disease, provided that the basement membrane lining the primary and secondary disease, provided that the basement membrane lining the filaments and lamellae remains intact. 相似文献
13.
Epitheliocystis infection affecting the gill and the pseudobranch of the cultured amberjack, Seriola dumerili Risso, is described. In hyperinfected fish, proliferative cell response around the epitheliocystis capsule resulted in gill and pseudobranch lamellar fusion, which led to mass mortalities in the 0+age class. Histopathological and scanning electron microscope observations showed that the target cell was the chloride cell since (1) epitheliocystis organisms were first found within the chloride cell; (2) chloride cells underwent degeneration in the filament epithelium, proliferated along the lamellae, and hypertrophied; and (3) cysts were found only in the trailing edge of the gill filament and in the interlamellar spaces where, in healthy fish, chloride cells are mainly located. In some cases, the pseudobranch of infected fish was much more severely affected than the gill. It is therefore suggested that, for diagnostic purposes, the pseudobranch should also be sampled when epitheliocystis disease is suspected. 相似文献
14.
运用石蜡切片技术和扫描电镜技术对稀有鮈鲫(Gobiocypris rarus)鳃结构进行观察,并采用浓度为2 mg/L的Cd Cl_2水溶液对稀有鮈鲫进行急性毒理实验。结果显示:稀有鮈鲫具4对鳃,由鳃耙、鳃弓、鳃丝及鳃小片组成。鳃的各个部位表面均有上皮细胞覆盖;鳃耙和鳃弓具味蕾,鳃弓上还具不同类型的黏液细胞;相邻鳃小片的上皮细胞间也分布有黏液细胞,在鳃小片基部有氯细胞着生。鳃丝表面有不规则凹陷和微嵴,具沟、坑、孔等结构;鳃小片两面均呈凹凸状。在2 mg/L的Cd Cl_2水溶液暴露下,鳃受到损伤,发生鳃小片充血呈球状,鳃上皮水肿、脱落,黏液细胞增多等现象;并随时间延长受损程度加重。 相似文献
15.
Abstract Vascular corrosion casting methods were used to elucidate the pathological effects of X-cell disease on the blood supply to the gills of the Antarctic teleost, Pagothenia borchgrevinki (Boulenger, 1902). Afferent and efferent branchial arteries were patent in X-cell diseased fish; however, the blood supply to the lamellae was markedly reduced or obliterated in areas in which there was a predominance of X-cells. The present authors believe that the tissue hyperplasia associated with X-cell disease results in the compression of the lamellar vascular bed which leads eventually to the occlusion of vessels. 相似文献
16.
Atlantic salmon were exposed to amoebic gill disease (AGD) immediately following their acclimatization to sea water (group 1), or following a 2 week period of maintenance in sea water (group 2). Three fish from each group were sampled on days 0, 1, 2, 4, 7, 14 and 28 post-infection. Characteristic gill lesions began to occur between days 2 and 4, and dramatically increased by day 7. The number of gill lesions on fish from group 2 was significantly higher than on fish from group 1 on days 7 and 14 ( P <0.001), but the two groups did not differ in any other parameter. Histologically, Paramoeba sp., the aetiological agent of AGD, could be seen on the gills of fish as soon as 1 day post-exposure, attached to healthy-appearing gills. Gill pathology in the form of hyperplasia and lamellar fusion followed shortly. AGD infection was accompanied by a significant increase in the number of gill mucous cells ( P =0.002). Different methods for the diagnosis of AGD are discussed. 相似文献
17.
W. E. HAENSLY J. M. NEFF J. R. SHARP † A. C. MORRIS M. F. BEDGOOD P. D. BOEM ‡ 《Journal of fish diseases》1982,5(5):365-391
Abstract. Organ samples were collected from plaice, Pleuronectes platessa L., captured in the highly oiled Aber Wrac'h and Aber Benoit at five intervals during the period 1978-1980, following the Amoco Cadiz crude oil spill. Reference plaice were obtained along the western and southern coasts of Brittany. Tissue samples were fixed, processed and stained by routine histologic procedures for qualitative and quantitative histopathological examination. The predominant lesions and conditions which characterized fish from the oiled estuaries were: fin and tail necrosis, hyperplasia and hypertrophy of gill lamellar mucous cells, gastric gland degeneration, decreased hepatocellular vacuolation (lipid), increased concentration of hepatic macrophage centres and lateral trunk muscle fibre degeneration. Dilation of Bowman's space, glomerular hypertrophy and abdominal muscle fibre degeneration were pronounced at the last sampling interval. Other types of lesions were seen at a lower frequency: hyperplasia and fusion of gill lamellar epithelium, telangiectasis of gill capillaries, hepatopancreatic degeneration and hepatic necrosis. Fish muscle and liver collected for biochemical analysis to detect the presence or absence of petroleum hydrocarbons were negative for Amoco Cadiz oil fractions. At the same time oysters, Crassostrea gigas Thunberg, collected from the oiled estuaries throughout the study period, showed high levels of Amoco Cadiz oil fractions. These data, along with the type and frequency of lesions observed, suggested that the plaice had been chronically-exposed to petroleum hydrocarbons of Amoco Cadiz origin. Some relief from chronic pollutant exposure was indicated by a decrease in gill mucous cell concentration at the last sampling interval. An increase in abdominal muscle fibre degeneration and an increase in the frequency of dilation of Bowman's space with glomerular hypertrophy at the last sampling interval suggested a latent response to the polluting agent. 相似文献
18.
L.J.S. Brokken P.M. Verbost W. Atsma S.E. Wendelaar Bonga 《Fish physiology and biochemistry》1998,18(4):331-342
Biochemical and immunological characteristics of peroxidase activity of the skin epithelium of common carp (Cyprinus carpio) were investigated and compared with peroxidase activity of blood cells. Skin as well as blood-borne peroxidases eluted from the Superdex column as a 135 kDa protein and both probably are tetrameric molecules. Skin peroxidase activity was characterized by a Vmax of 51.5 ± 1.3 U mg-1 min-1 and a KM of 1.64 ± 0.18 mM ortho-phenylenediamine (OPD), whereas blood-borne peroxidase was characterized by a 1,000 fold higher specific activity (Vmax = 30.5 103 ± 2.5 103 U mg-1 min-1) and a higher affinity (KM = 0.875 ± 0.003 mM OPD). Polyclonal antibodies were raised against concanavalin-A purified skin peroxidase as well as blood-borne peroxidase. Immunocytochemical labelling showed that peroxidase is present in mucous cells and in mucus covering the skin and gill epithelia, as well as in erythrocytes and leucocytes. We conclude that the mucous cells of the skin produce a biochemically distinct peroxidase that is released in the mucus and may contribute to the antimicrobial properties of the mucous layer covering the skin. After exposure of the fish to cadmium the kinetic characteristics of the enzyme activity, as determined in skin homogenates, changed considerably. The Vmax increased significantly to 61.9 ± 1.1 U mg-1 min-1, and the affinity for OPD increased to the value demonstrated for blood-borne peroxidase (KM = 0.888 ± 0.045 mM OPD). Increased peroxidase levels after cadmium exposure were also demonstrated immunochemically in a dotblot assay. However, no significant changes were observed when the circulatory system of the fish was perfused prior to sampling, indicating that erythrocytes are a major contributor to the increased peroxidase activity in carp skin during cadmium exposure. This likely reflects the increased vascularization of the connective tissue layer underlying the skin epithelium, which takes place when the fish are exposed to chronic stressors including cadmium. In the cadmium-exposed fish this effect prevented the biochemical detection of stressor-related changes in epithelial peroxidase reported earlier with cytochemical methods. 相似文献
19.
D A Graham W Curran H M Rowley D I Cox D Cockerill S Campbell & D Todd 《Journal of fish diseases》2002,25(4):227-234
An annual disease problem with high levels of mortality in Atlantic salmon, Salmo salar L., on a freshwater farm was investigated. In 2000, mortalities began early in October and peaked in December, being unevenly distributed between tanks. Histopathological changes included severe hyperplasia of gill epithelium, with fusion of secondary lamellae, and extensive necrosis of the haematopoietic centres in the kidney and spleen, the latter being consistent with a diagnosis of phagocytolytic syndrome (PCLS). Moribund fish were anaemic, with multiple, circular basophilic inclusion bodies, 1–2 μm in diameter and suggestive of erythrocytic inclusion body syndrome (EIBS), being observed on blood smears. Thin section electron microscopy (EM) revealed primarily membrane-bound aggregates of non-enveloped virus particles (73 ± 7 nm) with an electron dense core (35 ± 3 nm) in spleen, kidney and gill tissue and the erythrocytes therein. These particles had morphology and distribution consistent with those previously described separately for both EIBS and PCLS. Virus isolation attempts in a wide range of cell lines were unsuccessful. In the absence of suitable alternative infectious or environmental explanations, it is postulated that the aetiology was primarily viral, with possible contributory secondary environmental factors. It is further hypothesized that the agents of EIBS and PCLS may be the same or closely related viruses. 相似文献
20.
Abstract. Brown trout gills were examined after exposure to different aluminium concentrations (50, 200,500μg/1) at pH 5.5 and 7.0 for up to 6 weeks. The influence of humus (Pt 0, Pt 20) and water temperature (2.5°C, 15°C) was recorded. The gill structure was studied by light, scanning and transmission microscopy, together with a complementary morphometric analysis of centrally located secondary lamellae. Low water temperature (2.5°C) resulted in advanced gill lesions after exposure to aluminium at pH 5.5. The lesions were characterized by enlargement of the secondary lamellae due to an increased number of chloride cells in the epithelia. Furthermore, the chloride cells contained cytoplasmic aluminium precipitates. Addition of humus (Pt20) or increased pH (7.0) reduced or inhibited the effects of aluminium on the gills. A high water temperature (15°C) reduced the early gill lesions observed after exposure to water at 2.5°C. Prolonged exposure to a temperature of 15°C resulted in alterations in the gill structure in all groups, including the control group. 相似文献