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N Gas

Publications and source records attributed to N Gas.

At least 55 records · Page 3Linked to original sources
PubMed1982

Ultrastructure of endocrine cells in the stomach of two teleost fish, Perca fluviatilis L. and Ameiurus nebulosus L.

In the gastric mucosa of two teleost species, the perch (Perca fluviatilis) and the catfish (Ameiurus nebulosus) three endocrine cell types were found, located predominantly between the mucoid cells of the gastric mucosa. A fourth cell type is present in the gastric glands of catfish. Each cell type was defined by its characteristic secretory granules. Type-I cells were predominant in both fish. These cells contained round or oval granules with a pleomorphic core. The average diameter of granules was 400 nm for the perch and 270 nm for the catfish. Type-II cells of both species displayed small, highly osmiophilic granules about 100 nm in diameter. The secretory granules of type-III cells (260 nm in the perch and 190 nm in the catfish) were round or slightly oval in shape and were filled with a finely particulate electron-dense material. Type-IV cells of the catfish were found in the gastric glands only. Their cytoplasm was filled with homogeneous, moderately electron-dense granules averaging 340 nm in diameter. The physiological significance of these different morphological types of gastric endocrine cells requires further investigation.

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PubMed1979

Structure and function of the intestinal epithelial cells in the perch (Perca fluviatillis L.).

An ultrastructural study of the intestinal absorptive epithelium in perch (Perca fluviatilis) has shown that the perch intestine can be divided into three segments: the proximal segment, the middle segment and the distal segment. The enterocytes of the proximal segment are found to be concerned with lipid absorption. The adsorbed fat gives rise to the presence of two forms of inclusions: lipid particles and lipid droplets. Enterocytes of the middle segment exhibit the typical ultrastructural features of pinocytosis; these consist of extensive invaginations of the luminal surface membrane and acculation of vacuoles in the apical cytoplasm. Exogenous proteins are ingested by absorptive cells from the intestinal lumen by a process similar to that described in neonatal mammals. In the distal segment the absorptive cells have few, short microvilli. Besides the absorptive epithelial cells, goblet cells, endocrine cells, pear-shaped cells, and plasma cells are occasionally found.

Animals↗
PubMed1976

Electron microscopic study on gut epithelium of the tench (Tinca tinca L.) with respect to its absorptive functions.

Few morphological differences are seen along the intestinal tract of the adult tench (Tinca tinca L.) a stomachless freshwater teleost. However, three segments can be distinguished, when function and structure of enterocytes are studied. The enterocytes of the proximal segment are found to be concerned with dietary lipids absorption. In the cell, absorbed fats are seen in two inclusion bodies: lipid particles and lipid droplets. Only lipid particles are involved in direct transport of absorbed fatty acids in the blood circulation, as in lymphatic vessels. Lipid droplets seem to be involved in temporary storage of fatty acids. Special features are found in enterocytes of the short middle segment; these cells show many invaginations and pinocytosis figures, a well-developed tubulo-vesicular network and large vacuoles in the supranuclear hyaloplasm. Such characters bear a resemblance to descriptions of the gut of some newborn mammals. The great permeability of this epithelium to macromolecules is demonstrated by the administration of horseradish peroxidase (HRP). Enterocytes of the distal segment show, at their basal pole, numerous invaginations of the plasma membrane, and a large mitochondrial population. Morphological similarity suggests a functional analogy with epithelia involved in water and ions transport.

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