<p>This 3-D fluorescence image of a cancer tumor spheroid model shows how when clearing protocols are applied, it is possible to measure signal from inside the sphere (right) which is otherwise dark because the microscope cannot measure the light from deep inside tissues (left).
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Credit: NCATS
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/64860478@N05">National Center for Advancing Translational Sciences</a> from Bethesda, MD
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/64860478@N05/40813889460/">3-D Image of Cancer Tumor</a>