. The elasmobranch fishes. Chondrichthyes. THE ELASMOBRANCH FISHES 135 Stomach Tlie stoinacli of Elasmobranchs when seen in ventral view is a U- or J-shaped tube (for types see figs. 173 to 175, and ). the left arm of which, as in Heptanchus, is the cardiac and the right arm the pyloric division. The great variety in shape of the stomach found among the Elasmobranchs is due largely to variation in the relative length of the pyloric arm. In some, although the pyloric division is small in diameter, in length it is practically equal to the cardiac (leopard shark, fig. 173a; Raja); in oth
. The elasmobranch fishes. Chondrichthyes. THE ELASMOBRANCH FISHES 135 Stomach Tlie stoinacli of Elasmobranchs when seen in ventral view is a U- or J-shaped tube (for types see figs. 173 to 175, and ). the left arm of which, as in Heptanchus, is the cardiac and the right arm the pyloric division. The great variety in shape of the stomach found among the Elasmobranchs is due largely to variation in the relative length of the pyloric arm. In some, although the pyloric division is small in diameter, in length it is practically equal to the cardiac (leopard shark, fig. 173a; Raja); in others this arm is less than one-half the length of the cardiac, so that the shape of the stomach in these is better described as a J (Acanthias). In still others the pyloric limb is onl,y a small projection from the cardiac divi- sion of the stomach (Scynmus licliia, fig. 135b; Laemargus rostratus, fig. 136b). In the latter there is a so-called "blind sac" () at the angle. The mucous lining of the adult stomach is thrown into folds which, as we have said, may be continuous with those of the oesophagus. The folds on the walls of the cardiac division are high and may extend in part as the finer folds into the py- loric limb, but those of the two regions are usually distinct. A section through the mucosa of the stomach of Squalus acanthias according to Ringoen (1919; fig. 134) shows a gland as long and flask-shaped. The superficial epithelial cells (ejJ.) are somewhat like those found in the oesophagus, that is, they are columnar or pyramidal cells, the upper part of which contains a plug of mucus (pi.). The cells lining the median part of the crypt are large and their nuclei are vertical in position. In the deeper crypts are the gastric cells that are peculiar to the cardiac stomach. They lie at the base of the crypts and are large and granular and of a polygonal shape with their nuclei taking a more or less horizontal position. These are the true peptic cells (pc), w
Size: 1016px × 2460px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookpublisherberkeleycalifuniversityofcaliforn
