Stomachless Fish Research Articles

Evidence for somatostatin, gastrin and pancreatic polypeptide-like substances in the mucosa cells of the gut in fishes with and without stomach.

Gastrin, pancreatic polypeptide and somatostatin immunoreactive cells in the gut of two fish with stomachs (perch and catfish) and a stomachless fish (carp) were studied by immunocytochemistry. In the gastric mucosa of perch and catfish, cells showing gastrin and somatostatin-like immunoreactivity are found, scattered among the surface mucous cells and mucous neck cells. No pancreatic polypeptide (P.P.) immunoreactive cells are detected in the gastric mucosa. Cells showing gastrin and P.P.-like immunoreactivity are observed in the intestinal mucosa of perch, catfish and carp. In this location no somatostatin immunoreactive cells are found.

Correlation between digestion rate and feeding frequency in the stomachless teleost, Blennius pholis L.

Foregut emptying in Blennius pholis at 16–18°C is exponential (St=Soe‐Rt; R=0.006 when t is in min and s in mg dry weight). In consequence, the time for the foregut to empty completely varies in proportion to ln (meal size) in a chosen size of fish or to ln (body weight) in different sized fish fed to the same relative amount (% body weight). Appetite returns rapidly in comparison with other species (4–15 h for fish of 0.5−30 g) and, because of the tidal constraints imposed on this littoral fish, voluntarily ingested meals are large (14–9% body weight depending on fish size). Studies on digestion in small, stomachless fish are not adequately made using X‐radiography and must be supported by sequential gut samples after a meal.

Growth and diet dependant structural adaptations of the digestive tract in juvenile grass carp (Ctenopharyngodon idella, Val.)

The morphology of the intestinal epithelium is described and compared with published data. In the gut of this stomachless fish, three zones can be distinguished based on light and electron microscopic observations of absorptive cells: a rostral zone with numerous fat droplets, a second zone with large P.A.S.‐positive supranuclear vacuoles and pinocytotic vesicles, and a third zone without these characteristics. In these zones deep invaginations of the cell membrane is a feature of the basal part of the cells. The presence of pinocytotic vesicles in the second zone is considered evidence of the uptake of undigested protein‐like substances.Juvenile grass carp from 15 to 335 days, fed on either animal or vegetable food, were measured. The growth rates indicate that animal food stimulates rapid growth. The data also show a vegetable diet causes a slight increase in relative gut length, mainly in the length of the first zone.

A comparative study of wax ester digestion in fish

1.1. Purified wax ester, n-[1-C14]hexadecyl-myristate, was force-fed to a variety of marine fish representing seven species and five families, including two families of stomachless fish. Fish were held 48 hr without food then force-fed tracer along with either cold hexadecyl-myristate or vegetable oil as carrier. Fish were killed approximately 24 hr after feeding.2.2. All species incorporated activity into their tissue lipids but the % of total activity incorporated was greatly affected by the nature of the carrier and the architecture of the alimentary tract.3.3. Analyses of intestinal contents and tissue showed only trace amounts of radioactive alcohol. No detectable oxidation of alcohol occurred in 15 min assays of intestinal fluid.4.4. The results indicate that fish possess a general facility for hydrolysis of wax ester followed by oxidation of the released alcohol and subsequent incorporation of the resulting fatty acid into acyl lipids.5.5. Digestion of food in the intestine of fish is considerably aided by the presence of certain morphological characteristics such as the pyloric caeca whose blind pouches insure retention of food and provide an increased surface area.

A phylogenetic study on the occurrence and distribution of histamine in the gastro-intestinal tract and other tissues of man and various animals

Using a specific fluorimetric and biological method, the occurrence and distribution of histamine was investigated in man, various mammals, birds, reptiles, amphibians, bony and cartilaginous fishes, lancelets, tunicates, echinoderms, molluscs, and crustaceans. The amine was identified by the fluorescence spectrum, by specific antihistaminics in the bioassay, by the comparison of the fluorimetric histamine values following three different isolation procedures, and in some tissues also by thin-layer chromatography. Histamine was found in all chordates in considerable concentrations with the exception of the stomachless carp. The distribution of histamine in the body, however, varied largely from species to species. Only the gastric mucosa of all vertebratesinvestigated was relatively rich in histamine. The amine was nearly uniformly distributed in amphibians and fishes, in which only the stomach and partly the intestinum showed higher histamine concentrations than all the numerous other tissues investigated. The distribution of histamine, however, in mammals, birds, and reptiles showed great variations from tissue.to tissue. Organs free from histamine were first found in fishes going backward in the phylogeny. Because of the great variabilities in the distribution of histamine in the body of numerous species which were studied in this investigation, only one hypothesis can be developed with respect to a common physiological significance of histamine: there is a selective accumulation of histamine in the gastric mucosa of all chordates possessing acid-secreting cells and a low concentration of histamine in the gastro-intestinal tract of stomachless fishes. The gastric acid secretion is stimulated by histamine in all vertebrates investigated, whereas in many fishes histamine has no effects on the circulation or on smooth muscles of the gastro-intestinal tract or on the uterus. Thus, stored histamine probably has a specific function in the gastric mucosa, but not a general function, such as the regulation of ubiquitous metabolic processes or the regulation of microcirculation.

澱粉基質膜法によるティラピアおよびブルーギルの消化器官におけるアミラーゼ活性の局在

The purpose of this study is to detect the localization of amylase activity of fish which are possessed of the stomach or both the stomach and the pyloric caeca by a starch substrate film method, and to make clear the question whether other organs than the pancreas are concerned with the secretion of amylase. In Mozambique mouthbrooder amylolytic activity was found in the pancreatic exocrine tissues, at the luminal surfaces and the lumen of the intestine, and at the outer- and outside of the tracts of the stomach and the intestine. In bluegill the activity was found also in the pancreatic exocrine tissues; at the luminal surfaces and the lumen of the esophagus, the stomach, the pyloric caeca and the intestine; and at the outer- and outside of the wall of the pyloric caeca and the intestine. In both the examined species the mucosa and submucosa showed to be amylase-negative throughout the digestive tract. In sections of the pyloric caeca of bluegill and of the intestine of both species, stained with hematoxylin and eosin, pancreatic ramifications were found to be embedded in or adhere to the wall of the tracts. From the present evidences it seems that amylase production is confined to the pancreatic exocrine cells alone and the mucosal epithelial cells of the digestive tract are not associated with production or secretion of amylase. The present results are accordant with those obtained for the carp, a stomachless fish, which was earlier examined.

An electron microscope study of the columnar epithelial cell in the intestine of fresh water teleosts: goldfish (Carassius auratus) and rainbow trout (Salmo irideus).

The columnar epithelial cells of the intestine in goldfish and rainbow trout were studied by electron microscopy. The most striking feature of the columnar cells, which was common in both fishes, was the extensive formation of lamellar structures in the cytoplasm. These were actually ribbon-like sheets which were bounded by two regular parallel membranes, and were found mainly in the basal half of the cytoplasm. In profile, these lamellar sheets were similar to the basal infoldings in the distal convoluted tubules of kidney, but were independent of the basal plasma membrane. The function of these lamellae is not known; however, these are presumably the structure involved in transport of water or nutrients. The remarkable difference between the goldfish and trout intestine was the occurrence of the invaginations of luminal surface between microvilli, and a variety of vesicles and vacuoles in the apical cytoplasm, observed exclusively in the posterior intestine of goldfish. In the present paper, it is suggested that there are differences in kind or degree of absorption between the goldfish and the rainbow trout, probably between stomachless fish and stomach-possessing fish in general, and that in the former food materials are ingested into the cell of posterior intestine by vigorous pinocytosis.

PERISTALSIS, SEGMENTATION, AND THE MYENTERIC REFLEX

PERISTALSIS, SEGMENTATION, AND THE MYENTERIC REFLEX