The fine structure of the gastric epithelium of the rainbow trout, Salmo gairdneri, Richardson

Abstract

Fine structural characteristics of the columnar mucus cells lining the surface and pits of the gastric mucosa, oxyntic cells lining the glands and the gastric endocrine cells were studied. The surface mucus cells, in addition to their primary involvement in production of mucus, showed structural adaptations. Release of the mucus vesicles was achieved by exocytosis. Transition from pit gland cells was abrupt since no mucus neck cells were observed. The oxyntic cells possessed apical and basal microvillous processes, a well developed tubulovesicular system, zymogen granules and extensive RER associated with many large mitochondria. When stimulated by distension of the stomach, the apical cytoplasm was converted into a labyrinth of cytoplasmic processes, while annular lamellae, each of which showed a short peripheral linear density appeared in the basal cytoplasm. The endocrine cells showed apical modifications as microvilli, cilia and reduced glycocalyx covering. Three types were distinguished on the basis of their granular morphology.

Distribution, histochemistry and ultrastructure of somatostatin-like immunoreactive cells in the gastroenteric tract of the cartilaginous fishScyliorhinus stellaris (L.)

“…This discrepancy could be related to different fixatives, technical procedures and antibodies used. As in bony fish (Ezeasor, 1981) and protochordates (Pestarino, 1983) all somatostatin-like cells are in contact with the lumen, even in the gastric portion, and generally have cytoplasmic processes which are relatively short in S. stellaris.…”

A study of morphology and histology of the alimentary tract of Glyptosternum maculatum (Sisoridae, Siluriformes)

“…Observations at ultrastructural level showed that three types of cells (mucous, glandular and endocrine cells) were found in the stomach epithelium. According to Ezeasor (1981), mocus and glandular cells were involved in producing gastric juice. In other teleost fishes, the cells in the gastric glands are also called as oxyntopeptic cell, which are related to the synthesis of hydrochloric acid as well as pepsinogen.…”

A comparative histological and histochemical study of the post‐gastric alimentary canal from three species of pleuronectid, the Atlantic halibut, the yellowtail flounder and the winter flounder

“…The pinocytotic uptake and subsequent intracellular digestion of exogenous proteins by rectal epithelia has been documented frequently in both larval fish and adult stomachless fish (Noaillac-Depeyre & Gas, 1976;Watanabe, 1981Watanabe, , 1984Govoni et al, 1986;Caceci & Hrubec, 1990;Abaurrea et al, 1993). In stomachless species, protein digestion occurs intracellularly in the rectal epithelium (Govoni et al, 1986), as also in species with functional stomachs (Ezeasor, 1981;Morrison, 1987), probably increasing protein digestion efficiency, when gastric emptying is too frequent for complete hydrolysis of proteins in the stomach (Ezeasor, 1981). In a case such as this, the pinocytosis of proteins by the rectal cells would serve complementary to stomach function.…”