Related Experiment Video
Updated: Jul 30, 2026
10:24
Preparation of 3D Collagen Gels and Microchannels for the Study of 3D Interactions In Vivo
Published on: May 9, 2016
STEM/TEM studies of collagen fibril assembly
D F Holmes1, H K Graham, J A Trotter
1Wellcome Trust Centre for Cell-Matrix Research, School of Biological Sciences, University of Manchester, Stopford Building 2.205, Oxford Road, M13 9PT, Manchester, UK. david.holmes@man.ac.uk
Micron (Oxford, England : 1993)
|September 28, 2000
Summary
Quantitative scanning transmission electron microscopy (STEM) reveals collagen fibril assembly patterns. Tissue-formed fibrils exhibit unique tip growth, informing models of extracellular matrix organization.
Area of Science:
- Biophysics
- Materials Science
- Cell Biology
Background:
- Collagen fibrils are crucial components of the extracellular matrix (ECM).
- Understanding collagen fibril assembly is key to comprehending tissue development and repair.
- Quantitative analysis of fibril structure provides insights into molecular organization.
Purpose of the Study:
- To quantitatively analyze collagen fibril assembly using scanning transmission electron microscopy (STEM).
- To investigate differences in fibril tip growth between in vitro and in vivo environments.
- To develop computational models of collagen fibril formation based on experimental data.
Main Methods:
- Quantitative scanning transmission electron microscopy (STEM) for mass-per-unit-length measurements.
- Generation of axial mass distribution (AMD) profiles along collagen fibrils.
- Development of computer models simulating fibril assembly (e.g., diffusion-limited aggregation, interface-limited growth).
Main Results:
- STEM analysis enabled precise calculation of collagen molecule numbers per fibril section.
- Fibrils formed in tissue environments displayed a distinct tip growth characteristic with an abrupt change in mass slope.
- This tip growth pattern was observed across evolutionarily diverse species, including vertebrates and echinoderms.
- Computer models based on STEM data proposed two primary mechanisms for fibril growth: diffusion-limited aggregation and interface-limited growth.
- STEM data also indicated regulated inter-fibrillar fusion contributing to fibril growth in vertebrate tissues.
Conclusions:
- Collagen fibril assembly in vivo is characterized by a specific tip growth mechanism not observed in vitro.
- STEM-derived data and computational modeling provide fundamental insights into collagen fibril formation and extracellular matrix organization.
- The findings have implications for understanding how cells synthesize and organize collagenous tissues.
Related Concept Videos
01:56Structural Protein Function
Structural proteins are a category of proteins responsible for functions ranging from cell shape and movement to providing support to major structures such as bones, cartilage, hair, and muscles. This group includes proteins such as collagen, actin, myosin, and keratin.
Collagen, the most abundant protein in mammals, is found throughout the body. In connective tissue, such as skin, ligaments, and tendons, it provides tensile strength and elasticity. In bones and teeth, it mineralizes to form...
Collagen, the most abundant protein in mammals, is found throughout the body. In connective tissue, such as skin, ligaments, and tendons, it provides tensile strength and elasticity. In bones and teeth, it mineralizes to form...
01:18Assembly of Cytoskeletal Filaments
Cytoskeletal filaments are polymeric forms of smaller protein subunits. However, individual cytoskeletal filaments may easily disassemble or associate with other similar filaments to form rigid structures. Microfilaments, made of actin monomers, rely on actin-binding proteins to form bundles and create networks of individual actin filaments. Microtubules rely on microtubule-associated proteins (MAPs) to form sturdy cylindrical structures. However, the proteins involved in forming complex...
01:13Collagens are the Major Structural Proteins of ECM
Three main types of fibers are secreted by fibroblasts: collagen fibers, elastic fibers, and reticular fibers. Collagen fiber is made from fibrous protein subunits linked together to form a long, straight fiber. Collagen fibers, while flexible, have great tensile strength, resist stretching, and give ligaments and tendons their characteristic resilience and strength. These fibers hold connective tissues together, even during the body's movement.
Connective tissue proper includes loose...
Connective tissue proper includes loose...
01:11Fibril-associated Collagen
Fibril-associated collagens are a type of collagens present in the extracellular matrix with interrupted triple helices or FACIT (Fibril-associated collagens interrupted triple-helices). FACIT help connect and attach the collagen fibrils with each other as well as with other proteins of the extracellular matrix.
For example, the type II collagen fibrils in cartilage have covalently bound type IX fibril-associated collagens at regular intervals. Other types of fibril-associated collagens are...
For example, the type II collagen fibrils in cartilage have covalently bound type IX fibril-associated collagens at regular intervals. Other types of fibril-associated collagens are...
01:05Type IV Collagen of Basal Lamina
Type IV collagen is a 400 nm long, network-forming collagen that acts as a barrier between the epithelial and endothelial cells. Type IV collagen forms the backbone of the basement membrane by scaffolding with laminin, entactin, proteoglycans, and fibronectin. Apart from rendering structural support to the basement membrane, it also helps entail signaling potentials necessary for both pathological and physiological functions.
A type IV collagen molecule has six alpha chains which can exist in...
A type IV collagen molecule has six alpha chains which can exist in...
00:55Fibrous Proteins
Fibrous proteins are either long and narrow proteins or assemble to form long and thin structures. They contain repetitive units and usually consist of either alpha helices or beta sheets and, in rare cases, a mix of both. The amino acids in the primary structure often consist of repeating amino acid sequences. The role of fibrous proteins is primarily structural. Many are located in the extracellular matrix and are present in connective tissues to impart strength and joint mobility. They are...