Endochondral Ossification
Endochondral ossification is the process that forms all long bones in the mammalian skeletal system. It involves the replacement of hyaline cartilage with bony tissue.
Endochondral ossification begins when:
- Mesoderm-derived mesenchymal cells differentiate into chondrocytes
- Chondrocytes proliferate rapidly and secrete an extracellular matrix to form the cartilage model for bone
The process begins in the diaphysis at a primary ossification center and proceeds at multiple secondary ossification centers in the epiphyses. The steps of endochondral ossification include:
- Cartilage enlarges; chondrocytes die
- Blood vessels grow into perichondrium; cells convert to osteoblasts
- More blood supply and osteoblasts; produces spongy bone; formation spreads on shaft
- Osteoclasts create medullary cavity; appositional growth
Endochondral ossification is one of the two essential processes during fetal development of the mammalian skeletal system by which bone tissue is produced. The other process is intramembranous ossification.
In babies, thyroid helps with bone growth (turning cartilage into bone) by stimulating and regulating endochondral ossification.
- Osteochondrosis is a family of orthopedic diseases of the joint that occur in children, adolescents and rapidly growing animals, particularly pigs, horses, dogs, and broiler chickens. They are characterized by interruption of the blood supply of a bone, in particular to the epiphysis, followed by localized bony necrosis, and later, regrowth of the bone. This disorder is defined as a focal disturbance of endochondral ossification and is regarded as having a multifactorial cause, so no one thing accounts for all aspects of this disease.