COLLAGEN IMAGES

A false-coloured scanning electron micrograph of collagen (connective tissue) removed from a human knee during arthroscopic surgery.

Credit: Anne Weston, LRI, CRUK, Wellcome Images.

Connective tissue

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. • Credit: Mike Kayser, Wellcome Images

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Calcified bone interface

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.

Credit: Martin Knight, Wellcome Images

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Ruptured tendon

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.

Credit: Professor Giorgio Gabella, Wellcome Images

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Smooth muscle cells

Aspartic acid is coded for in the genome and therefore is 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. It plays an important part in the citric acid (or ‘Krebs’) cycle in energy

production and can stimulate NMDA receptors. It is therefore thought to help concentration and brain function.Credit: Maurizio De Angelis, Wellcome Images.

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Collagen fibrils and mast cell granules

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. Credit: Rob Young, Wellcome Images

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Degenerating collagen fibrils in glaucoma

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.

Credit: Rob Young, Wellcome Images

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Collagen fibrils with proteoglycans

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.

Credit: Rob Young, Wellcome Images

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Meshwork of collagen fibrils

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. Credit: Rob Young, Wellcome Images

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Type II collagen fibril in vitro

Glycine is coded for in the genome and is consequently 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 several products. Credit: Maurizio De Angelis, Wellcome Images

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Glycine

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.

Credit: Rob Young, Wellcome Images

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Network of collagen fibrils

Human skin contains many layers, including the epidermis and the dermis. This image of the dermis layer of skin shows fibroblasts and thick collagen bundles (connective tissue). Credit: Ivor Mason, Wellcome Images

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Human skin

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. Credit: Rob Young, Wellcome Images

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Collagen fibril forming in vitro

A colour-enhanced scanning electron micrograph of a network of collagen. Credit: David Gregory and Debbie Marshall, Wellcome Images

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Collagen network

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