A Non-Invasive, Label-Free Method for Examining Tardigrade Anatomy Using Holotomography

Holotomography is an advanced imaging technique that enables high-resolution, three-dimensional visualization of microscopic specimens without the need for fixation or staining. By applying this technology, we successfully imaged live Hypsibius exemplaris in their native state, avoiding invasive procedures and phototoxic effects. Using a low concentration of 7% ethanol for tardigrade sedation and sample preparation, we captured detailed, label-free 3D images of both external and internal structures, including the digestive tract, brain, ovary, claws, salivary glands, and musculature. These findings highlight holotomography as a complementary high-resolution imaging modality that effectively addresses challenges faced with traditional imaging techniques in tardigrade research.