Bone cells are located in small cavities in the concentric layers of mineralized matrix.
When young, they are called osteoblasts (from Greek osteonbone and blasts, “Young cell”) and have long cytoplasmic projections that touch neighboring osteoblasts. By secreting the intercellular matrix around them, osteoblasts are trapped inside small cameras, from which channels containing the cytoplasmic projections depart.
When the bone cell becomes mature, it becomes osteocyte (from Greek osteonbone and kyton, cell), and their cytoplasmic extensions retract, so that it occupies only the central gap. The canaliculi where the extensions were used serve as communication between one gap and another, and it is through them that the nutritive substances and oxygen gas from the blood to the bone cells.
In addition to osteoblasts and osteocytes, there are other important cells in bone tissue: osteoclasts (from Greek klastos, break, destroy). These cells are especially active in destroying damaged or aged areas of the bone, paving the way for tissue regeneration by osteoblasts. Scientists believe that bones are continually being remodeled by the joint activity of destruction and reconstruction undertaken by osteoclasts and osteoblasts respectively. You will find more information about osteoclasts in the text on bone remodeling.