Collagen images

Explore this important protein in the image gallery below

Collagen is a fibrous protein that provides structural support to tissues. In our bodies, it is found in connective tissues in bone, teeth, tendons, ligaments, cartilage, artery walls and elsewhere. Collagen accounts for around one-third of all protein in vertebrates. 

Calcified bone interface

A transmission electron micrograph showing the layers of cells at the interface of calcified bone. The layer of cells across the middle are the osteoblasts. These cells are packed with endoplasmic reticulum (indicating protein synthesis) and are laying down the osteoid – the uncalcified collagen matrix (above the osteoblasts). To the right is a developing osteocyte, and a mature osteocyte is visible in the top centre. The black material is calcified bone.

CC BY Mike Kayser/Wellcome Collection

Ruptured tendon

A coloured confocal image showing damaged collagen fibres in a ruptured tendon. The area of wavy fibres to the lower right shows the normal appearance of a healthy tendon. The waviness allows the whole tendon to have a small amount of elasticity (2–10 per cent) as the collagen fibres themselves do not stretch. The field of view is approximately 220 microns across.

CC BY Martin Knight/Wellcome Collection

Smooth muscle cells

A transmission electron micrograph of visceral smooth muscle cells in the intestine. It shows features of the cell membrane, myosin and actin microfilaments, intermediate filaments (cytoskeleton), mitochondria, sarcoplasmic reticulum, caveolae, and collagen fibrils.

CC BY Professor Giorgio Gabella/Wellcome Collection

Collagen

A transmission electron micrograph of collagen fibres. Collagen is a protein found only in animals and is the main component of connective tissue. It’s also found in fibrous tissue in long bundles, the structure of which is shown in this image.

CC BY NC Dr David Furness/Wellcome Collection

Collagen fibrils and mast cell granules

A transmission electron micrograph showing mast cells, including detail of the scroll-type cytoplasmic granule structure. Stromal collagen fibrils are also visible. This field is approximately 8 microns across.

CC BY NC Rob Young/Wellcome Collection

Degenerating collagen fibrils in glaucoma

A transmission electron micrograph showing collagen fibrils exhibiting focal swelling and loss of periodic cross-banding in the trabecular meshwork of a person with glaucoma. The trabecular meshwork is the structure through which the aqueous humour in the anterior chamber drains into Schlemm’s canal. The obstruction of this process may represent a mechanism by which the intraocular pressure is raised in glaucoma. The proteoglycans that are normally attached to the collagen fibrils have become detached and are seen as small short filaments. The intact fibrils are approximately 120 nm in diameter.

CC BY NC Rob Young/Wellcome Collection

Collagen fibrils with proteoglycans

A transmission electron micrograph showing collagen fibrils in the sclera. At the top of the picture, they are seen in longitudinal section; towards the bottom, they are seen in transverse section. The attached proteoglycans are seen as fine filaments on the fibrils running radially, axially and around the fibrils. The fibrils are approximately 130 nm in diameter.

CC BY NC Rob Young/Wellcome Collection

Meshwork of collagen fibrils

A transmission electron micrograph showing a meshwork of collagen fibrils typical of Bowman’s layer, below the epithelium of the cornea. This field is approximately 4 microns across.

CC BY NC Rob Young/Wellcome Collection

Type II collagen fibril in vitro

A transmission electron micrograph showing the assembly of type II collagen molecules into a cross-banded fibril from individual collagen molecules in vitro. The banding pattern represents the alignment of charged amino acids together with mass differences that exclude (light bands) or accumulate (dark bands) the stain. The banding repeat is approximately 65 nm. Finer filamentous assemblies surround the main fibril.

CC BY NC Rob Young/Wellcome Collection

Glycine

Glycine is coded for in the genome and is therefore a non-essential amino acid, which means that it can be produced by the body and doesn’t need to come from the food we eat. Glycine is normally only required in small amounts with the exception of collagen, which is composed of a high percentage of glycine molecules. It’s also used to produce many naturally occurring products and as an additive in a number of products.

CC BY Bruce Kirchoff/Flickr

Network of collagen fibrils

A transmission electron micrograph of type XI collagen fibrils forming in vitro from a solution of the collagen protein purified from chondrosarcoma tissue. Type XI collagen is found in cartilage, intervertebral discs and the vitreous humour of the eye.

CC BY NC Rob Young/Wellcome Collection

Collagen fibril forming in vitro

A collagen fibril forming in a test tube from a solution of purified collagen protein. The new molecules arrange themselves at the tip of the fibril in an organised way, and the result of the precise alignment of the individual collagen molecules is a typical pattern of light and dark bands across the fibril. This self-assembly is a naturally occurring process like those exploited in various forms of nanotechnology. Collagen forms the basis of a lot of the connective tissue in the body and is becoming increasingly popular as a cosmetic treatment for filling out wrinkles, lips and old scars.

CC BY NC Rob Young/Wellcome Collection

Collagen network

A colour-enhanced scanning electron micrograph of a network of collagen.

CC BY David Gregory and Debbie Marshall/Wellcome Collection

Image research by Iona Twaddell and captions by Rosie Cotter, adapted from Wellcome Collection unless stated otherwise.

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About this resource

This resource was first published in ‘Proteins’ in January 2014.

Topic:
Cell biology
Issue:
Proteins
Education levels:
16–19, Continuing professional development

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