J.Jpn. Surg. Soc.. 58(3): 384-394, 1957

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STUDIES ON THE DEVELOPMENT OF THE STOMACH AS A RESERVOIR IN THE LOWER VERTEBRATE(HARD-BONED FISH)
1. MORPHOLOGICAL STUDIES OF THE STOMACH AS A RESERVOIR

The upper portion of the digestive tract of the hard-boned fish was compared morphologically and histologically; the findings obtained were considered from the view point of reservoir function.
The results are as follows :
Stomach-lacking fish such as Carassius auratus or Misgurnus anguillicaudatus, has its initial portion of midgut distended to be a substitute stomach, and in stomachpossessed fish, a prat of foregut changed to a stomach as a resuit of being dilated.
Stomach shows the different steps of development as from the primitive tubular stomach of Mogurnda obscura, the sac-formed stomach of Parasilurus asotus to the blind sac formation in the stomach of Channa argus or Anguilla japonica.
The wall of the reservoir portion is thick with weII developed muscular layer and submucous tissue, and its interior surface has high rough folds, thus adapting itself for the accumulation and accomodation of food.
The outlet part of the reservoir is small in diameter, kinked or distorted, thus limiting the passage of the food. Further in Mogurnda obscura or Parasilurus asotus a structure acting like a sphinctric ring and in Channa argus or Anguilla japonica the formation of pyloric sphincter is observed.
Thus the author has demonstrated that, with due consideration of the influences of food habit on the morphology of digestive tract, even in stomach-lacking fish there was seen a structure like reservoir or the upper digestive tract before the development of gastric glands, and the stomach-possessed fish the stomach showed the progressive stage of development. Finally the author stresses the importance of reservoir function in organism.
(author's abstract)

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