Structure and carbohydrate histochemistry of the intestine in ten teleostean species

Abstract

The morphology and carbohydrate histochemistry of ten teleostean intestines are compared. Although there is an absence of regional differentiation seen in higher vertebrates, specializations in some species occur in the form of intestinal swellings, pyloric ceca and recta, the latter separated by a valve. The intestinal lumen is lined by a simple columnar epithelium interspersed with goblet cells; multicellular intestinal glands are absent. Thick basement membranes seen in centrarchids and Perca flavescens closely resemble the stratum compactum found in the lamina propria of esocids. Granular cells, which vary in number from species to species, are often seen in the mucosa and submucosa but less frequently in the muscularis. In species with intestino-rectal valves, a rectum is easily defined by the abrupt appearance of lower mucosal folds, more goblet cells and a thicker muscularis. In the remaining species the above features appear gradually in the distal intestine. Goblet cells show species variations in localization of epithelial mucosubstances, which in broad terms are recognized as sulfomucins, sialomucins and neutral mucosubstances. In both proximal and distal intestines the majority of goblet cells contain sialomucin although small amounts of sulfomucin are also often present. In species without intestino-rectal valves, no changes in carbohydrates occur between proximal and distal intestines. The possible significance of the heterogeneous character of digestive tract mucosubstances is discussed.

Histochemical differences along the intestine of Corydoras paleatus (Siluriformes: Callichthyidae)

“…In the I1 of C. paleatus, the MC were scarce and had a low content of highly sulfated mucins and a high content of weak acid mucins. This result agrees with those obtained previously for teleosts of the orders Perciformes, Cypriniformes, Esociformes, Siluriformes, Beloniformes and Salmoniformes (Reifel & Travill, 1979;Tibbets, 1997;Podkowa & Goiakowska-Witalinska, 2002;Marchetti et al, 2006;Hernández et al, 2009). In this catfish, the AB combined techniques allowed the identification of three types of MC.…”

The physiology of digestion in fish larvae

“…Longitudinally oriented smooth muscle in the muscularis is absent in larvae and does not develop until transformation. Whereas the longitudinal folds of the larval foregut compare well with the convolutions of the esophagus of adult fishes, the mid-and hindgut mucosa lack the distinct villi and crypt-like indentations of adults (Reifel & Travill 1979). Instead, the mucosa forms shallow rugae.…”

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

“…The fish stomach has been defined as a widening of the intestine i.e., an intestinal bulb by PrCTET (1909) and ROGrCK (1931), because of the absence of gastric glands and a similar epithelium, in both regions (KHANNA 1971;GAUTHIER & LANDfS 1975;SfNHA & MOITRA 1974;VERMA & TYAGf 1974;REIFEL & TRAVILL 1979;CHAVES & VAZZOLER 1984). However, the stomach may also be classified as a true organ as it may have two distinct histological regions: the anterior cardic region with gastric glands and the posterior pyloric region without gastric glands (DALELA 1969;Y ADA V & SfNGH 1980;ROM BOUT & TA VERNE-THJLE 1982;UUBARRIE 1982;MARTIN & BLABER 1984;MURRA Yet al 1994).…”