What is the Difference Between Tonofibrils and Tonofilaments?

Tonofibrils and tonofilaments are both cytoplasmic structures found in epithelial tissues, but they have distinct compositions and functions:

Tonofibrils:

• Protein structures primarily found in epithelial tissues.
• Connect at desmosomes and hemidesmosomes.
• Composed of thin fibrils that connect to the cytoskeletal structures.
• Visible clusters of tonofilaments.
• Provide a framework to the cell and support cell-to-cell adhesion, providing resistance to abrasion.

Tonofilaments:

• Keratin intermediate filaments found in epithelial tissues.
• Bundle together to form tonofibrils.
• Made of keratin proteins.
• Especially noticeable under desmosomal plaques.
• Loop through desmosomes in epithelial cells and interact with intracellular proteins found in the plaques.
• Interact with hemidesmosomes.

In summary, tonofibrils are composed of bundles of tonofilaments, and they provide structure and support to epithelial cells. Tonofilaments are the keratin intermediate filaments that make up tonofibrils and play a role in cell adhesion and interaction with other intracellular proteins.

Comparative Table: Tonofibrils vs Tonofilaments

Here is a table comparing the differences between tonofibrils and tonofilaments:

In summary, tonofibrils are cytoplasmic fibrils made up of bundles of keratinous intermediate filaments called tonofilaments. Tonofilaments are composed of 8 intermediate keratin filaments K5 and K14. Both tonofibrils and tonofilaments are components of the cytoskeleton of animal cells, found in desmosomes between epithelial cells, and attached to the inner membrane of the desmosomes. Tonofibrils provide a framework to the cell and support cell-to-cell adhesion, while tonofilaments interact with other intracellular attachment proteins in desmosomes.