The bone shown in this page had all its soft tissue removed mechanically and chemically, then was washed, left to dry and finally sectioned longitudinally.
Upper figure
Two kinds of arrangements of bone tissue can be observed.
The outmost layer of the whole bone, the cortical bone, is made of a very dense bone tissue called compact bone. Sections of compact bone viewed with a microscope show thousands of very small spaces. This type of bone is very resistant to tension, torsion and mechanical shocks.
The inner of this bone contains millions of small plates of bone tissue, the trabeculae (singular: trabecula) also called spicules. Their spatial arrangement creates a large amount of spaces that can be seen with the naked eye. In vivo the spaces are filled with bone marrow.
Because of the combination of plates and cavities, this type of bone is called spongy , cancellous or trabecular bone.
The trabeculae of the spongy bone are arranged according to the lines of force acting on the bone, turning the spongy bone lighter than the compact bone, although also very resistant to mechanical forces.
Macrophotograph of a dry bone.
Lower figure
A higher magnification of spongy and compact bone.
The outer layer of the bone is formed by compact bone (in red). Most of the image is occupied by bone trabeculae of spongy bone.
After placing the mouse cursor over the image or clicking on the image:
The light pink areas are surfaces of bone trabeculae. The dark red areas indicate lacunae between trabeculae. The arrows point to trabeculae.
Cross-sections of trabecullae observed with a microscope appear as lines or rods.
