The ampullate silk gland of the spider, Araneus sericatus, produces the silk fiber for the scaffolding of the web. The fine structure of the various parts of the gland is described. The distal portion of the duct consist of a tube of epithelial cells which appear to secrete a substance which forms the tunica intima of the duct wall. At the proximal end of the duct there is a region of secretory cells. The epithelium of the sac portion contains five morphologically distinct types of granules. The bulk of the synthesis of silk occurs in the tail of the gland, and in this region only a single type of secretory droplet is seen in the epithelium. Protein synthesis can be stimulated by the injection of 1 mg/kg acetylcholine into the body fluids. 10 min after injection, much of the protein stored in the cytoplasm of the epithelial cells has been secreted into the lumen. 20 min after stimulation, the ergastoplasmic sacs form large whorls in the cytoplasm. Protein, similar in electron-opacity to protein found in the lumen, begins to form in that portion of the cytoplasm which is enclosed by the whorls. The limiting membrane of these droplets is formed by ergastoplasmic membranes which lose their ribosomes. No Golgi material has been found in these cells. Protein appears to be manufactured in the cytoplasm of the tail cells in a form which is ready for secretion.
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1 July 1969
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July 01 1969
CHANGES IN FINE STRUCTURE DURING SILK PROTEIN PRODUCTION IN THE AMPULLATE GLAND OF THE SPIDER ARANEUS SERICATUS
Allen L. Bell,
Allen L. Bell
From the Department of Anatomy, University of Colorado Medical Center, Denver, Colorado 80220, and the Department of Pharmacology, Upstate Medical Center, Syracuse, New York 13210
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David B. Peakall
David B. Peakall
From the Department of Anatomy, University of Colorado Medical Center, Denver, Colorado 80220, and the Department of Pharmacology, Upstate Medical Center, Syracuse, New York 13210
Search for other works by this author on:
Allen L. Bell
From the Department of Anatomy, University of Colorado Medical Center, Denver, Colorado 80220, and the Department of Pharmacology, Upstate Medical Center, Syracuse, New York 13210
David B. Peakall
From the Department of Anatomy, University of Colorado Medical Center, Denver, Colorado 80220, and the Department of Pharmacology, Upstate Medical Center, Syracuse, New York 13210
Received:
May 29 1968
Revision Received:
February 14 1969
Online ISSN: 1540-8140
Print ISSN: 0021-9525
Copyright © 1969 by The Rockefeller University Press.
1969
J Cell Biol (1969) 42 (1): 284–295.
Article history
Received:
May 29 1968
Revision Received:
February 14 1969
Citation
Allen L. Bell, David B. Peakall; CHANGES IN FINE STRUCTURE DURING SILK PROTEIN PRODUCTION IN THE AMPULLATE GLAND OF THE SPIDER ARANEUS SERICATUS . J Cell Biol 1 July 1969; 42 (1): 284–295. doi: https://doi.org/10.1083/jcb.42.1.284
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