US researchers have found a way to make rodent skin transparent and take a peek at the flesh beneath.
By injecting certain chemicals into a hamster's skin the researchers were able to look through a small patch of flesh and see previously hidden blood vessels.
The research team at Texas University in Austin think the process could have wide applications for medical diagnosis and new therapies.
Glycerol, the most powerful of the substances used, stops light being scattered through flesh, effectively creating a temporary "window".
The various components in skin and tissue, including water, scatter or refract light to different extents, making skin and tissue opaque.
Clear view
The process is similar to the effect of shining a torch into fog. The different sized water droplets in the fog scatter light in many directions causing a general glow.
Glycerol can change the degree of scattering through small areas of tissue by two different mechanisms.
Firstly, glycerol pulls water out of cells causing them to shrink. The researchers believe the shrinkage may bring certain tissue components, such as collagen fibres, closer together, modifying the way light is scattered.
Secondly, it changes the optical composition of tissue because the glycerol that replaces the water refracts light to a similar extent as many other skin components.
Reversible process
Eventually water moves back into the cells rendering the tissue opaque again.
Research team member Gracie Vargas told BBC News Online: "We can now see four to five millimetres deep as opposed to just one."
This extra depth could be of use in light-based diagnostic and therapeutic medical techniques. However researchers do not yet know if the process is safe to use on humans.
"Glycerol is used in cosmetics and for medical applications," said Ms Vargas.
"But at this stage we are interested in how the process works. A lot more studies will have to be done to find out which substances can be safely used."
Commenting on the research, Dr Charlotte Proby, consultant at the Imperial Cancer Research Fund's Skin Tumour Laboratory at the Royal London Hospital said: "This new technique could potentially be very useful for skin procedures such as laser treatment.
"It is unlikely to replace biopsy and histopathology in the diagnosis of malignant tumours as doctors need to examine the characteristics of individual cells," she told BBC News Online.