Periosteum is a tissue fabric layer on the outside of bone, as seen in the upper diagonal segment of the tissue image volume. The natural weave of elastin (green) and collagen (yellow) are evident when viewed under the microscope. Elastin gives periosteum its stretchy properties and collagen imparts toughness. Muscle is organized into fiber bundles, observed as round structures in the lower diagonal segment of the tissue image volume. The volume is approximately 200 x 200 microns (width x height) x 25 microns deep.