High-resolution electron microscopy of interlysosomal junctions

Our plain-English summary of High-resolution electron microscopy of interlysosomal junctions, by D. Beju (Ultrastructural Pathology, 1988).

The study

• Author: D. Beju
• Journal: Ultrastructural Pathology
• Published: 1988;12(3):307-16
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Five different malignant tumors and two nasal polyps were examined by electron microscopy for diagnosis purposes. In all cases occasional large cells containing lysosomes interconnected by characteristic junctions were observed. The interlysosomal junctions appeared organized in zig-zag and ladder like configurations. The ultrastructural and morphometric analyses of these junctions postulated that the two configurations represented the same structure viewed in two different sectioning planes. High-resolution electron microscopic evidence suggests that the interlysosomal junction is organized as a 35-40 A thick pleated ribbon extending between a 200-A wide interlysosomal space, in close contact with the adjoining lysosomal membranes, without apparent integration into the membrane.

In plain English

This was an electron microscopy study, by a single author, of surgical tissue specimens examined for diagnosis: two nasal polyps, two astrocytomas, one adenocarcinoma, one fibrous histiocytoma and one mesothelioma. The article does not say where the mesothelioma arose, and it does not discuss asbestos or any other exposure. In all specimens, occasional large cells contained lysosomes (small sacs inside cells) linked by junctions that appeared in zig-zag and ladder-like patterns. The author measured 100 profiles of these junctions and over 200 lysosome profiles. The linked lysosomes averaged 643 plus or minus 263 nm across. In the zig-zag pattern, the components measured 200 plus or minus 30 Å long and 35 plus or minus 4 Å thick, set at a constant angle of 58 plus or minus 4 degrees. High-resolution images suggested globular subunits about 34 Å across. The author concluded that both patterns are one structure, a pleated ribbon resembling an "accordion door", seen in different section planes. The author also concluded that the term "interlysosomal junction" should replace "zipperlike junction". The author stated that the junctions' function remains to be evaluated by means other than static morphology.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Descriptive electron microscopy and morphometric (measurement) study of surgical specimens examined for diagnosis
• Who was studied: Surgical tissue specimens: two nasal polyps, two astrocytomas, one adenocarcinoma, one fibrous histiocytoma and one mesothelioma (site not stated). Micrographs of 100 junction profiles and over 200 lysosome profiles were measured. Place and period of collection were not stated beyond the author's Tulsa and Oklahoma affiliations.
• Exposure: No exposure was studied. The article examined cell structures in tissue and does not mention asbestos or any fiber type.
• Main results:
  • In all specimens, occasional large cells contained lysosomes interconnected by characteristic junctions.
  • The junctions appeared in two basic patterns, zig-zag and ladderlike.
  • The lysosomes linked by junctions had an average diameter of 643 plus or minus 263 nm. Most had a form factor of 0.85 to 0.96, indicating slightly ellipsoid and round shapes.
  • In the zig-zag pattern, the linear components measured 200 plus or minus 30 Å in length and 35 plus or minus 4 Å in thickness, at a constant angle of 58 plus or minus 4 degrees.
  • High-resolution images suggested a globular substructure, with subunits of approximately 34 Å in diameter.
  • The author's structural model proposed 34 Å-thick ribbons pleated at a constant 58 degree angle, resembling an "accordion door" rather than a zipper.
• The authors' conclusion: The author concluded that the zig-zag and ladderlike patterns are sections through a single pleated-ribbon junctional system rather than two separate structures. The author also concluded that the term "interlysosomal junction" should replace "zipperlike junction".
• Limitations the authors state:
  • The author stated that the significance and function of these junctions could not be determined from static morphological images and remain to be evaluated by other means.

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