What causes chondrocyte hypertrophy?
What causes chondrocyte hypertrophy?
Extrinsic factors such as bone morphogenetic proteins, Indian hedgehog, and modulators such as Sox9, Runx2, Smads, and histone deacetylase 4 are reportedly essential for chondrogenesis (1, 2). Loss of histone deacetylase 4 causes early onset of hypertrophy, followed by growth retardation (6).
What happens to chondrocytes during hypertrophy?
Chondrocytes that undergo hypertrophy-like changes produce a number of proteins that are involved in tissue remodeling and calcification. A number of (transcription) factors regulate the differentiation from a normal articular chondrocyte to a terminal differentiated chondrocyte.
What is the purpose of chondrocyte?
Chondrocytes in the AC proliferate and secrete extracellular matrix to maintain and sustain the cartilage. The cells themselves are separated from each other by cartilage matrix [2]. They respond to outside stimuli and tissue damage, and are also responsible for degenerative conditions, such as osteoarthritis (OA).
What is chondrocyte ossification?
During endochondral ossification, chondrocytes proliferate, undergo hypertrophy and die; the cartilage extracellular matrix they construct is then invaded by blood vessels, osteoclasts, bone marrow cells and osteoblasts, the last of which deposit bone on remnants of cartilage matrix.
What is the difference between Osteocyte and chondrocyte?
Osteocytes are developed in the mucoid connective tissue and a mature osteocyte contains a single nucleus. Chondrocytes are involved in the maintenance of cartilage. Osteocytes are involved in the maintenance of bone tissue. This is the difference between Chondrocytes and Osteocytes.
What do hypertrophic chondrocytes secrete?
More importantly, hypertrophic chondrocytes secrete critical paracrine factors, such as vascular endothelial growth factor (VEGF) that induce invasion of blood vessels from the perichondrium, and Indian hedgehog (Ihh) that regulate proliferation and differentiation of chondrocytes and directs perichondrial cells to …
Do Chondroblasts produce collagen?
Chondroblasts secrete the extracellular matrix which is composed of various substances, including collagen, proteoglycans, glycoproteins, hyaluronic acid, water, and macromolecules. They do this by secreting the extracellular matrix at the peripheral cartilage surfaces.
What type of cell is chondrocyte?
Cartilage cells
Cartilage cells, called chondrocytes, occur at scattered sites through the cartilage and receive nutrition by diffusion through the gel; cartilage contains no blood vessels or nerves, unlike bone.
What organelles are in a chondrocyte?
Chondrocytes’ size and shape vary depending on the anatomical layer, but all of them has organelles like endoplasmic retinaculum and Golgi membrane for matrix synthesis. Cytoskeleton of chondrocytes is composed of actin, tubulin and vimentin filaments.
Is chondrocyte a cartilage cell?
Cartilage cells, called chondrocytes, occur at scattered sites through the cartilage and receive nutrition by diffusion through the gel; cartilage contains no blood vessels or nerves, unlike bone.
What is a chondrocyte medical?
[ kŏn′drə-sīt′ ] n. A connective tissue cell that occupies a lacuna within (the )cartilage matrix. cartilage cell.
What is hypertrophy in ossification?
It forms through a multistep differentiation process in which chondrocytes differentiate, proliferate, stop dividing and undergo hypertrophy, which entails a 20-fold increase in size. Key words: endochondral ossification, hypertrophic chondrocytes, lineage, osteoblast.
What is the role of chondrocyte?
Chondrocytes in normal adult articular cartilage are stable, differentiated cells that maintain tissue homeostasis by synthesizing a very low level of ECM to replace damaged matrix molecules, thereby preserving the structural integrity of the cartilage matrix.
What layer is the zone of hypertrophy?
The topmost layer of the epiphysis is the reserve zone. The second zone, the proliferative zone, is where chondrocytes are continually undergoing mitosis. The next zone is the zone of maturation and hypertrophy where lipids, glycogen, and alkaline phosphatase accumulate, causing the cartilaginous matrix to calcify.
What happens to chondrocytes after they proliferate?
During this process, a cartilage template is formed in which chondrocytes proliferate and differentiate into hypertrophic chondrocytes and are gradu- ally replaced by bone. Postnatally, remnants of embryonic chondrocytes remain in a restricted domain between the ossified regions of the bones forming the growth plate.
What is difference between chondrocytes and osteocytes?
What is hypertrophy?
Hypertrophy is an increase and growth of muscle cells. Hypertrophy refers to an increase in muscular size achieved through exercise. When you work out, if you want to tone or improve muscle definition, lifting weights is the most common way to increase hypertrophy.
What is the difference between a Chondroblast and a chondrocyte?
Chondroblasts are a type of cells found in the cartilage which are responsible for the cartilage development. Chondrocytes are a type of specialized cells found in cartilage which are responsible for cartilage maintenance.
What is the function of lacunae?
Lacunae – Function The primary function of lacuna in bone or cartilage is to provide housing to the cells it contains and keeps the enclosed cells alive and functional. In bones, lacunae encase osteocytes; in cartilage, lacunae enclose chondrocytes.
How does a bone grow in thickness?
Even though bones stop growing in length in early adulthood, they can continue to increase in thickness or diameter throughout life in response to stress from increased muscle activity or to weight. The increase in diameter is called appositional growth.
When does a chondrocyte become a hypertrophic cell?
Chondrocytes undergo terminal differentiation when they become hypertrophic, which happens during endochondral ossification. This last stage is characterized by major phenotypic changes in the cell. The chondrocyte in cartilage matrix has rounded or polygonal structure.
What is the role of chondrocytes in osteoarthritis?
Chondrocyte hypertrophy is a characteristic of osteoarthritis and dominates bone growth. Intra- and extracellular changes that are known to be induced by metabolically active hypertrophic chondrocytes are known to contribute to hypertrophy.
Which is the least differentiated lineage of chondrocytes?
From least- to terminally-differentiated, the chondrocytic lineage is: Colony-forming unit-fibroblast (CFU-F) Mesenchymal stem cell / marrow stromal cell (MSC) Chondrocyte Hypertrophic chondrocyte
Where does the maturation of chondrocyte take place?
This process begins with a cartilage anlage where chondrocyte cells will congregate and start their maturation process. Once the chondrocytes have fully matured at the desired rate, the cartilage tissue will harden into bone.