Histology of Compact Bone
Compact bone is found in the outer layers of most bones and the diaphysis of long bones.
I’ll start with a ground section of compact bone (in a ground section the bone still contains its hardened calcium matrix– so sections must be ground thin enough for histology rather than simply cutting them).
Next let’s look at some images of decalcified bone. Here the bone tissue has been treated with acid to remove the hardened calcium matrix, making it soft enough for sectioning.
Note in the above image that decalcified bone looks a bit different from ground bone, but the major features (osteons, central canals, lamellae, etc.) are still visible.
Spongy bone Histology
In the above image we see decalcified spongy bone. The lighter stained tissue here is bone, but in spongy bone the bone tissue is arranged with spaces between the bone tissue, that are filled with red bone marrow (stains a darker purple). The spaces allow spongy bone to be lighter than compact bone. The pieces of bone in spongy bone are also arranged so that they keep the bone strong… kind of like the cross beams and pillars in a steel building keep the building strong even though the building has lots of open spaces in the inside.
At high magnification we can see osteocytes inside of lacunae.