Page 58 - Headlines Histology2024_Neat

Functions

• Osteoblasts are responsible for the formation of organic components of
bone matrix (osteoid tissue).

• They secrete matrix vesicles that participate in the nucleation of
crystalline bone minerals.

• Resorption of osteoid tissue (unmineralized matrix).
3) Osteocytes (mature bone cells)

• The osteocytes are the principal cells of mature bone.
• They are located inside lacunae within calcified bone matrix.
• They are less active than osteoblasts and cannot divide inside their

lacunae. The cell body is flattened with numerous cytoplasmic processes
that extend through tiny channels within the bone matrix called
canaliculi.
• The processes of the adjacent cells are interconnected with each other
via gap junctions permitting flow of ions and small molecules between
blood and osteocytes.
• With LM, the nuclear and cytoplasmic characteristics are similar to
those of osteoblasts except the Golgi region is less prominent and the
cytoplasm is less basophilic.
• With EM, the rER and the Golgi are still prominent; however, osteocytes
situated deeper in bone matrix may have less prominent rER and Golgi
saccules.
Functions

• Preserve and maintain the integrity of the bone matrix.
4) Osteoclasts

• They are large (about 50 ?m) multinucleated cells lining in depressions
on the bone surface called Howships lacunae.

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