X-ray microtomographic imaging of three-dimensional structure of soft tissues.

We report the x-ray microtomographic imaging of three-dimensional (3D) structure of soft tissues. The transparency of biological tissue to hard x-rays enables radiographic analysis of tissue entrails. However, biological tissues are mainly composed of light elements, which produce little contrast in a hard x-ray transmission image. Tissue structures were visualized by contrasting biological constituents with heavy elements. Efficient x-ray absorption by heavy-element dyes allowed the radiographic visualization of microstructures of soft tissues. The high-resolution computed tomography analysis provided the 3D microstructure of these microcontrasted tissues. Element-selective visualization of the stained tissue using x-ray absorption edges revealed the specific architecture of internal components. The structures obtained were used for rapid prototyping, giving 3D copies of human capillary vessels and fruit fly body.