The key difference between osteon and osteocyte is that osteon is a cylindrical vascular tunnel formed by an osteoclast-rich tissue while osteocyte is a mature bone cell embedded in the mature bony tissue.
Compact bone, also known as cortical bone, is a denser and stronger bone tissue. Compact bone consists of closely packed osteons. The osteon consists of a central canal called the osteonic canal. The osteonic canal is surrounded by concentric rings of the matrix. Between these rings of matrix, bone cells called osteocytes are located in spaces known as lacunae. Therefore, osteon and osteocyte are components of a compact bone. They play a pivotal role in bone metabolism.
CONTENTS
1. Overview and Key Difference
2. What is Osteon
3. What is Osteocyte
4. Similarities – Osteon and Osteocyte
5. Osteon vs. Osteocyte in Tabular Form
6. FAQ – Osteon and Osteocyte
7. Summary – Osteon vs. Osteocyte
What is Osteon?
Osteon is the primary structural and functional unit of a compact bone. It is also known as the Haversian system. Osteons are found in the bones of several mammals, birds, reptiles, and amphibians. An osteon is several millimeters in length and has a diameter of 0.2 mm. An osteon runs in a direction that is perpendicular to the primary axis of a bone.
Osteon has a cylindrical structure composed of concentric layers of bone tissue called lamellae. Lamellae surrounds a central canal called the Haversian Canal. Moreover, this canal contains several smaller blood vessels that are responsible for supplying blood to osteocytes. The functions of the osteon may include providing strength to the bone, influxing nutrients to the bone, and removing waste from the bone.
Figure 01: Osteon and Osteocyte
What is an Osteocyte?
Osteocyte is an oblate-shaped type of bone cell that is commonly found in mature bone. Osteocytes can live as long as the organism itself. The human body has about 42 billion of them. Osteocytes do not divide, and they have an average half-life of 25 years. In a mature bone, osteocytes reside inside spaces called lacunae and canaliculi. Sometimes, scientists simply describe osteocytes as osteoblasts trapped in the matrix that they secrete.
Osteocyte is the most abundant type of bone cell in mature bone tissue. It is usually capable of bone deposition and resorption. Furthermore, osteocyte is also involved in bone remodeling and may help in calcium removal from the bone when the calcium level of the body drops too low.
What are the Similarities Between Osteon and Osteocyte?
- Osteons and osteocytes are components of a compact bone.
- Osteocytes are arranged as a network of gap junction coupled cells in each osteon.
- Both play a pivotal role in bone metabolism.
- They play an important role in bone remodeling and renewal.
What is the Difference Between Osteon and Osteocyte?
An osteon is a cylindrical vascular tunnel formed by an osteoclast-rich tissue, while an osteocyte is a mature bone cell that is embedded in mature bony tissue. Thus, this is the key difference between osteon and osteocyte. Furthermore, osteon is the chief structural unit of a compact bone, while osteocyte is the most abundant type of bone cell in mature bone tissue.
The infographic below presents the differences between osteon and osteocyte in tabular form for side-by-side comparison.
FAQ: Osteon and Osteocyte
What is the function of osteocytes?
Osteocytes help in the regulation of local mineral deposition and chemistry at the bone matrix level. They also function as endocrine cells, producing factors that target distant organs such as the kidney to regulate phosphate transport.
What surrounds an osteocyte?
Osteocytes are encased within lacunae, within the mineralized bone matrix.
What do osteocytes contain?
Osteocytes contain glutamate transporters that produce nerve growth factors after bone fracture.
Summary – Osteon vs. Osteocyte
Osteon is the primary structural and functional unit of a compact bone. It is a cylindrical structure composed of concentric layers of bone tissue called lamellae, which surrounds a central canal. On the other hand, osteocyte is the most abundant type of bone cell in mature bone tissue that resides inside spaces called lacunae and canaliculi. Hence, this summarizes the difference between osteon and osteocyte.
Reference:
1. “Osteocyte.” Encyclopædia Britannica, Encyclopædia Britannica, inc.
2. “Osteon.” An Overview | ScienceDirect Topics.
Image Courtesy:
1. “Transverse section of bone en” By Source digital bitmap graphics: BDBRecreated in vector format: Nyq – Original analog graphics: Gray’s Anatomy of the Human Body from the classic 1918 publication available online at Bartleby.com: Own work (CC BY-SA 4.0) via Commons Wikimedia