"To find these pockets of interstitial fluid, medical...

"To find these pockets of interstitial fluid, medical researchers looked at living tissues instead of sampling dead tissue samples. They did this by using a probing technique called confocal laser endomicroscopy.
The method entails using a tiny camera probe that takes a microscopic look around a human body. Tissue is lit by the endoscope's lasers and the fluorescent patterns is then reflects are analysed by sensors."
"I think what the paper shows is the benefit of having new ways to image and look at tissues. (Previous methods) dehydrate the tissues, and you lose so much structural information," Munson notes.

http://www.nationalgeographic.com.au/science/new-human-organ-was-hiding-in-plain-sight.aspx

Did they use a ViewnVivo for this. Great publicity for Endomicroscopy somebody pointed out to me!