Microscopic morphology and histochemistry of the digestive system of a tropical freshwater fish Trichomycterus brasiliensis (Lütken) (Siluroidei, Trichomycteridae)

Abstract

The digestive system of Trichomycterus brasiliensis (Lütken, 1874), a small sized tropical Teleostean fish widely distributed in South America, was studied. Tissue samples were prepared for light and scanning electron microscopy (SEM). Trichomycterus brasiliensis shows stratified esophagus epithelium with taste buds and goblet cells with neutral and acid mucus at the anterior region. The stomach is caecal, presenting a pyloric valve with neutral mucus cells. At the terminal portion it is surrounded by a thick muscular wall. The intestine shows two loops; the epithelium is single columnar, with acid and neutral mucus in goblet cells. Multicellular intestinal glands are absent. Granular cells are often seen in the mucosa, less in the submucosa but were not observed in the muscularis. After the intestine-rectal valve, the rectum shows lower mucosal folds, more goblet cells and a thicker muscularis. No lobes were observed at the liver. Small regions of pancreatic tissue may be identified within the hepatic tissue mainly surrounding vessels and ducts. A compact pancreas may also be observed ventrally to the stomach and covering the bile duct. The possible significance of the heterogeneous character of the digestive tube mucosubstances is discussed. The digestive system of T. brasiliensis presents structural characteristics of a predator fish

Morphological, histological and histochemical analysis of the digestive tract of Trachelyopterusstriatulus (Siluriformes: Auchenipteridae)

“…The epithelium described for the species in another study was similar to that of Ictalurus punctatus (Rafinesque, 1818) (SIS et al 1979), T. brasiliensis (OLIVEIRA-RIBEIRO & FANTA 2000), Rhamdia quelen (Quoy & Gaimard, 1824) (HERNÁNDEZ et al 2009), andG. maculatum (XIONG et al 2011).…”

“…In fact, eating insects like coleopterans, as described for the species under study (DIAS et al 2005), can cause injury to the oesophageal tissue, but the epithelium protects this layer. Mucous cells were observed in the oesophageal epithelium of T. striatulus, and they reacted positively to histochemical analysis, similar to P. maculatus (GODINHO et al 1970) and T. brasiliensis (OLIVEIRA-RIBEIRO & FANTA 2000), suggesting that this action of the mucus is associated to guiding different types of prey and lubricating the food, also described by OLIVEIRA- RIBEIRO & FANTA (2000) and XIONG et al (2011). Taste buds were observed in the oesophageal epithelium of T. striatulus and in the Siluriformes I. punctatus (SIS et al 1979), T. brasiliensis (OLIVEIRA-RIBEIRO & FANTA 2000), and G. maculatum (XIONG et al 2011).…”

“…Complementing analyses, such as morphological and stomach content analyses, are required. Histologically, the intestine of T. striatulus consists of a simple prismatic epithelium with brush border, prismatic and goblet cells, as described for species of Siluriformes studied by OLIVEIRA- RIBEIRO & FANTA (2000), SANTOS et al (2007), HERNÁNDEZ et al (2009), andXIONG et al (2011). The goblet cells reacted positively to the histochemical techniques employed, indicating the presence of neutral, acid, and sulphate mucus.…”

Histochemical, immunohistochemical, and ultrastructural observations of the esophagus morphology of Rinella icterica (Anuran, Bufonidae)

“…Acid glycoconjugates were also predominant in the esophageal mucosa of D. melanostictus (Loo and Wong 1975) as well as in fish, reptiles, birds, and mammals (Suganuma et al 1981;Imai et al 1992;Oliveira-Ribeiro and Fanta 2000;Ferri et al 2001). Acid glycoconjugates were also predominant in the esophageal mucosa of D. melanostictus (Loo and Wong 1975) as well as in fish, reptiles, birds, and mammals (Suganuma et al 1981;Imai et al 1992;Oliveira-Ribeiro and Fanta 2000;Ferri et al 2001).…”

Comparative morphology and cytology of the alimentary tract in lizardfishes (Teleostei, Aulopiformes, Synodontidae)

“…The more posterior intestine bears bone particles mixed with some fatty substances. It is possible that the diversity of gastric glands, as well as of several types of goblet cells as described by Oliveira-Ribeiro and Fanta (2000), in fact reflect, at least partly, the developmental ripening of the basic cell type. Wilson and Castro (2010) described the digestive gland cells as cubical, whereas in the studied lizardfishes they are pyramidal in form, with their narrower end facing the tubules lumen.…”