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(cell and molecular biology)
Any of the fibrils converging on desmosomes in epithelial cells.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



a filamentous formation in the epithelial cells of animals. While tonofibrils were previously thought to extend from one cell to another, electron-microscope investigations have disproved the notion that such formations are continuous. It has been shown that they converge in the region of the desmosomes, where they bend and reenter the core of the cell. The usual diameter of a tonofibril is approximately 60 angstroms. It is likely that tonofibrils ensure the mechanical stability of cells.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Numerous cytoplasmic filaments are observed, including tonofibrils; cytoplasmic glycogen is also present.
Others have suggested that the sarcomatoid component is also of epithelial origin because, in some studies, (2-3) the spindle cells have been shown to exhibit ultrastructural features of epithelial differentiation (desmosomes and tonofibrils).
The reported ultrastructural features of PCE include the presence of microvilli, lacy cytoplasm, and abundant tonofibrils. (16) To the best of our knowledge, these findings have not been compared to those of clear cell RCCs.