It is normally an ability associated with superhuman comic book heroes, but scientists have discovered a way of peering through the skin, muscles and bones of animals.
The technique turns the layers of tissue transparent, allowing researchers to peer into the body so they can see more delicate features like nerves and veins while they are still inside an animal’s body.
They have demonstrated the technique to provide high resolution 3D images of the brain and nervous system of an entire mouse.
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The technique allowed them to study the delicate structures like nerves and veins while they are still inside an animal's body
Scientists have developed a technique that allows them to turn skin, muscle and tissue completely transparent (pictured above) so they can study the delicate structures like nerves and veins while they are still inside an animal’s body
HOW TO TURN A BODY TRANSPARENT
Mammalian tissue is opaque because the cells that make it up are filled with water surrounded by oily molecules known as lipids.
These scatter light making it impossible to see through thick layers of tissue like muscle, bone, fat and skin.
The researchers found that if they removed the water by dehydrating the body, they could then remove the lipids using a solvent.
The process, however, fixes proteins in place. By filling cells with flourescent proteins, it is possible to view the fine detail of a structure like neurons in the brain.
Their technique could help in the study of diseases like Motor Neuron Disease, Alzheimer’s’ Disease and Parkinson’s Disease.
The scientists say they have already been able to use the technique to render large rodents like rats transparent and believe it could even be applied to larger mammals like monkeys.
Ultimately they hope to use it on human tissue to help map the human brain.
Dr Ali Ertürk, a researcher at the Institute for Stroke and Dementia Research at Ludwig Maximilians University of Munich, said: ‘We developed a major technology that allows making entire organs and organisms transparent.
‘The new method provides the basis to map neuronal, glial, and vascular connections in the entire lab animals and potentially in deceased human brains.’
The researchers used a technique known as tissue clearing to first remove the water by dehydrating it and the oily lipids that form cell membranes using a solvent.
The researchers used their technique on the bodies of mice and rats, showing they could see through the skin and skull to look at the brain underneath (pictured)
The researchers used their technique on the bodies of mice and rats, showing they could see through the skin and skull to look at the brain underneath (pictured)
The technique removes the water and oily lipids from the cells but fixes proteins. By flooding brain cells with fluorescent proteins, the researchers were able to produce detailed images of the mouse brain without having to dissect it, risking damage to the tissue
The technique removes the water and oily lipids from the cells but fixes proteins. By flooding brain cells with fluorescent proteins, the researchers were able to produce detailed images of the mouse brain without having to dissect it, risking damage to the tissue
Water and lipids can scatter light and are the main parts of mammalian tissues that make them opaque.
While tissue clearing has been used for decades to see through tissues, the new approach used by Dr Ertürk and his colleagues also makes it possible to make bones transparent too.
It builds on a technique known as 3D Imaging of Sovent-Cleared Organs, or 3DISCO. The team, whose work is published in Nature Methods, have called their approach Ultimate DISCO (uDISCO).
The images obtained by the researchers showed the brain and spinal cord of the mouse in extreme detail. They were able to obtain 3D images of the delicate tissue (pictured)
The images obtained by the researchers showed the brain and spinal cord of the mouse in extreme detail. They were able to obtain 3D images of the delicate tissue (pictured)
The tissue clearing technique can work on larger mammals such as rats (before process pictured)
The rat pictured after it had undergone the technique to turn its tissue transparent. The researchers say it could also be used on small monkeys and perhaps eventually the human brain
The tissue clearing technique can work on larger mammals such as rats (before pictured left and turned transparent right) and even small monkeys, the researchers say. They hope to develop it so it can also be used to study human brain tissue
It also allows them to express fluorescent proteins in certain tissues, like nerves, allowing them to image them in intricate detail.
Dr Ertürk compared it to being able to turn the concrete walls of a building into glass so they can see the pipes and cables that lie beneath.
He said: ‘Now we can see every pipe connection and easily identify if one is disconnected – like disconnected neurons in demented brains.
The researchers were able to image individual neurons using their technique as they wound through the body. The image above shows where neurons connect to the mouse whiskers
The researchers were able to image individual neurons using their technique as they wound through the body. The image above shows where neurons connect to the mouse whiskers
The technique also allowed the researchers to visualise the delicate blood vessels that surround the central nervous system of a rat. Normally these would be damaged if taking sections for use in previous scanning techniques
The technique also allowed the researchers to visualise the delicate blood vessels that surround the central nervous system of a rat. Normally these would be damaged if taking sections for use in previous scanning techniques
Detailed three dimensional maps of the mouse brain and nervous system (pictured) could be built up using the new imaging technique
Detailed three dimensional maps of the mouse brain and nervous system (pictured) could be built up using the new imaging technique
‘uDisco achieves transparency not only of a single wall but throughout the whole organism.’
The process also causes the bodies of the animals to shrink by up to 60 per cent but fixes the proteins in the cells in place.
By filling the cells of an animal with a floursecent protein they can then image intricate tissue structures.
Using different fluorescent proteins, the researchers are able to examine different structures in the bodies of the animals they studied simply by placing them under a microscope (pictured)
Using different fluorescent proteins, the researchers are able to examine different structures in the bodies of the animals they studied simply by placing them under a microscope (pictured)
Dr Ertürk said his team are now already working with other groups around the world to use the technique to study diabetes, stroke, inflammation and Alzheimer’s Disease.
He said it would also help in stem cell trails by allowing researchers to see if the cells had integrated into an animal’s tissue or migrated to other parts of the body where they could cause tumours.
He said: ‘I believe the applications are unlimited. Another precious application of method will be to map the human brain.
The bodies (pictured after treatement with flourescent proteins) also shrunk by around two thirds due to the way the technique is used. This could prove useful when studying larger animals as it would make them easier to handle
The bodies (pictured after treatement with flourescent proteins) also shrunk by around two thirds due to the way the technique is used. This could prove useful when studying larger animals as it would make them easier to handle
‘So far there is not any approach, which even comes close to mapping any part of human brain at individual neuron level.
‘Now for the first time we have a powerful tool that can make the human brain transparent and reduce it size to fit an imaging microscope for mapping.
‘However, how the post-mortem human brain neurons will be labelled with fluorescent signal remains a major challenge to be solved beforehand.’