It has long been a major challenge to acquire high-resolution image data from relatively large and complex biological samples (e.g., intact embryos, whole organs of animal models and thick tissue sections) to obtain a systems view of the biological question being studied. Most biological tissues are non-transparent; this is mainly attributed to the lipid bilayer that makes up the cellular membrane in each of the rather packed biological cells within the tissue. Light scattering at the lipid-water interphase (due to differences in refractive index) causes serious problems for imaging, making deep-tissue imaging extremely challenging (the penetration depths in such tissue using confocal and multi-photo imaging are only ~100 and ~500 µm, respectively). In 2013, an electrophoretic tissue clearing (ETC) technique, termed CLARITY, was introduced by Chung and colleagues (Nature 497, 332-337 (2013)) at Stanford University. Since then, they and numerous other research groups have shown how CLARITY could address most of these challenges using a wide variety of biological tissues.