The Biological bulletin (20189125570)

Title: The Biological bulletin

Identifier: biologicalbullet152mari (find matches)

Year: [1] (s)

Authors: Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ). Annual report 1907/08-1952; Lillie, Frank Rattray, 1870-1947; Moore, Carl Richard, 1892-; Redfield, Alfred Clarence, 1890-1983

Subjects: Biology; Zoology; Biology; Marine Biology

Publisher: Woods Hole, Mass. : Marine Biological Laboratory

Contributing Library: MBLWHOI Library

Digitizing Sponsor: MBLWHOI Library

Text Appearing Before Image:

72 HORI, TANAHASHI AND MATSUOKA

Text Appearing After Image:

FIGURE 10. Fine structure of an aggregate of the secretory granules found in the 1.7 M fraction obtained by sucrose density gradient centrifugation, showing the secretory granules of dense, light and core-hearing types as well as the surrounding rough-surfaced endo- plasmic reticulum. Scale bar is 1 /j.. Tht-ir failure in identifying the granules might he related to the morphological varia- tion of the ultrastructure of granules, because secretory granules in starfish pyloric caeca do not always appear as dense as those in mammalian pancreatic acini. As described above, some granules (light granules) are characterized by amorphous contents which (like the dense granules) are also azocarmine-positive. Therefore, if the specimens from the pre-breeding season were used for study, then the light granules could predominate. It would be difficult to identify the granules as zymogen morphologically, unless a careful comparison was made from light- and electron microscopic preparations. Morphologically, the dense granules appear to be the mature form and the granules having a dense core appear to be transitory forms between the light and dense granules. However, it is also possible that some core-bearing granules might have already been matured. Possibility also exists that the morphological heterogeneity of the granules might reflect their biochemical heterogeneity (i.e., different types of granules contain different sets of hydrolytic enzymes). The granular fraction obtained by sucrose density gradient centrifugation exhibited the same electrophoretic pattern of protease activity as that of the original tissue homogenates. However, this does not necessarily mean that each isolated granule- is biochemically equivalent. The dense granules in starfish pyloric caeca were morphologically quite similar to the secretory granules described by Holland and Lauritis (1968) in gastric exocrine cells of the purple sea urchin. Strongylocentrotus pui'piiratus. It is un-

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