ABSTRACT. Histology and histochemical characterization of the digestive tract of Pimelodus maculatus (Pimelodidae, Siluriformes) in Funil reservoir, Rio de Janeiro, Brazil. Histological structures of the digestive traits of Pimelodus maculatus La Cepède, 1803, in the Funil reservoir (22º30'-22º35'S; 44º35'-44º40'W) were described using haematoxilin-eosin (HE), trichome Gomori, periodic acid Schiff (PAS) and alcian blue (AB) pH 2.5 techniques. The main aim of this study was to detect the levels of glycoproteins (GPs) in the mucous tunic based in histochemical techniques and to characterize eventual alteration in the digestive tract of this species in a polluted system. Fifty-four adult individuals collected between April-2003 and July-2004 (TL=19-38 cm) were examined. The mucosa showed longitudinal folds in the buccopharyngeal cavity, with a stratified squamous epithelium. The oesophagus showed epithelium similar to buccopharyngeal cavity, with a predominance of mucous cells, which reacted strongly with the used methods. The stomach showed three regions: cardic, fundic and pyloric. The mucous tunic is continuously revested by a single cylindrical epithelium which showed positive reaction to AB and PAS only at the apical cells surface. The proper tunic has tubular glands that ramify gradatively, being a cellular type named oxyntopeptic, related to chloridric acid and pepsinogenic cells synthesis. The intestine showed vilosities, with the mucous tunic revested by a single cylindrical epithelium with striated planure and caliciform cells. The duodenum submucosa layer was located at the coledocum opening, as a single cylindrical epithelium lacking caliciforms cells, reacting positively with both PAS and AB. The eutrophic environment of Funil reservoir did not seem to influence morphologic patterns of the structures (oesophagus, stomach and intestine) and no modification was observed in the mucous cells activity. KEYWORDS.Morphology, glycoproteins, fishes, Pimelodidae. RESUMO. As estruturas teciduais do trato gastrintestinal dePimelodus maculatus La Cepède, 1803, do reservatório de Funil (22º30'-22º35'S; 44º35'-44º40'W) foram descritas através das técnicas de hematoxilina-eosina (HE), tricômico Gomori, ácido Periódico de Schiff (PAS) e alcian blue (AB) pH 2,5. Objetivou-se a detecção de glicoproteínas (GPs) na mucosa através de uma análise histoquímica e caracterização de possíveis alterações ao longo do trato digestório destes peixes neste sistema de elevado grau de alteração. Cinqüenta e quatro indivíduos adultos, coletados entre abril de 2003 e julho de 2004 (CT=19-38 cm) foram utilizados. Na cavidade bucofaríngea, a mucosa apresenta-se com pregas longitudinais e o epitélio é do tipo estratificado pavimentoso. O esôfago apresenta o mesmo tipo de epitélio da cavidade bucofaríngea, destacando-se a predominância de células mucosas que tiveram forte reação aos métodos utilizados. O estômago foi diferenciado em região cárdica, fúndica e pilórica. A mucosa é continuamente revestida por um epitélio simples cilíndrico que...

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The gonad morphology and spawning season of Loricariichthys spixii in Lajes reservoir

ABSTRACT. Relative abundance and distrib ution of Loricariic ht hys SplXII (Steindachner) (Siluriformes, Loricariidae) in the Lajes reservoir, Rio de Janeiro State, Brazil The armored calfish Loricoriichthys ~pixii (Sleindachner, 1882) is lhe mOSI abundanl member of lhe Loricariidae family in the Lajes reservoir (22°42'-22°50'S 43°53'-44°05'W), the largest dam in the State ofRio de Janeiro State, bullittle is known about its biology and life cyc\e. A standardized fish sampling program in tlu'ee zones of the reservo ir (Iower, middle and upper reaches), during three annual cyc\es: monthly in 1994/ 1996 and bi -monlhly in 1997 was conducted out aiming to assess and add knowledge of the population structure of this species. Fishes were caught using gill nels (50 m long, 3 m deplh and 25 to 45 mm meshes), amounting 160 samples. Water temperature, pH and transparency were registered at each sample to correlate with fish abundance. Loricariichthys ~pixii (Steindachner, 1882) was the most abundant fish species in the reselvoir, contributing about on third of the total nllmber and half ofthe tota l weight ofthe catches, but a decreasing trend was observed over the three year 01' the study, with num bel' and biomass being significantly more abundant in 1994, followed by 1996 and 1997. There is no clear dependence between environmental parameters and fish occurrence, excepl for the coincidence of decreasi ng tish abundance and decrcasing leveIs ofwater ofthe reservoir over the three year. Fishes were more abundant in lhe high and intell11ediate reaches ofthe reservoir, near to mOllth ofthe tributaries. Seasonally, there is no clear variation in relative abundance. The success of use of lhe reservoir by L. ~pixii could be atlributed to availability of l11uddy and sandy subslrate associated with its k-strategy by carrying eggs, which could allow this species fàces the environmenlal changes of the reservoir, mainly the variations in leveI of water, by hydroelectric power demand o KEY WORDS. Lajes, reservoir, Loricariidae, di stribution, environmental parameters.A famí lia Loricariidae reúne espécies vulgarmente conhecidas como cascudos e cascudos-vio la, sendo caracterizadas por apresentar o corpo revestido por p lacas ósseas, boca inferior e lábios desenvolvidos em forma de ventosa (NELSON 1994). Constituem um dos grupos mais numerosos de peixes Siluriformes neotropicais, compreendendo aproximadamente 600 espécies reconhecidas. Têm sua distribuição limitada à América do Sul e Centra1 -Panamá e Costa Rica (FOWLER 1954;NELSON 1994). REGAN (1904)

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