What is the difference between endochondral ossification and intramembranous ossification

The erosion of old bone along the medullary cavity and the deposition of new bone beneath the periosteum not only increase the diameter of the diaphysis but also increase the diameter of the medullary cavity.

However, in adult life, bone undergoes constant remodeling, in which resorption of old or damaged bone takes place on the same surface where osteoblasts lay new bone to replace that which is resorbed.

Injury, exercise, and other activities lead to remodeling. Those influences are discussed later in the chapter, but even without injury or exercise, about 5 to 10 percent of the skeleton is remodeled annually just by destroying old bone and renewing it with fresh bone. The severity of the disease can range from mild to severe. Those with the most severe forms of the disease sustain many more fractures than those with a mild form. Frequent and multiple fractures typically lead to bone deformities and short stature.

Bowing of the long bones and curvature of the spine are also common in people afflicted with OI. Curvature of the spine makes breathing difficult because the lungs are compressed.

Because collagen is such an important structural protein in many parts of the body, people with OI may also experience fragile skin, weak muscles, loose joints, easy bruising, frequent nosebleeds, brittle teeth, blue sclera, and hearing loss.

There is no known cure for OI. Treatment focuses on helping the person retain as much independence as possible while minimizing fractures and maximizing mobility. Toward that end, safe exercises, like swimming, in which the body is less likely to experience collisions or compressive forces, are recommended. Braces to support legs, ankles, knees, and wrists are used as needed. Canes, walkers, or wheelchairs can also help compensate for weaknesses. When bones do break, casts, splints, or wraps are used.

In some cases, metal rods may be surgically implanted into the long bones of the arms and legs. Research is currently being conducted on using bisphosphonates to treat OI. Smoking and being overweight are especially risky in people with OI, since smoking is known to weaken bones, and extra body weight puts additional stress on the bones.

All bone formation is a replacement process. During development, tissues are replaced by bone during the ossification process. In intramembranous ossification, bone develops directly from sheets of mesenchymal connective tissue. In endochondral ossification, bone develops by replacing hyaline cartilage. Activity in the epiphyseal plate enables bones to grow in length this is interstitial growth.

Appositional growth allows bones to grow in diameter. Remodeling occurs as bone is resorbed and replaced by new bone. Considering how a long bone develops, what are the similarities and differences between a primary and a secondary ossification center?

Skip to content Learning Objectives By the end of this section, you will be able to: Discuss the process of bone formation and development. List the steps of intramembranous ossification Explain the role of cartilage in bone formation List the steps of endochondral ossification Explain the growth activity at the epiphyseal plate Explain how bones remodel overtime Compare and contrast the processes of intramembranous and endochondral bone formation Compare and contrast the interstitial and appositional growth.

The longitudinal growth of bone is a result of cellular division in the proliferative zone and the maturation of cells in the zone of maturation and hypertrophy. Most of the chondrocytes in the zone of calcified matrix , the zone closest to the diaphysis, are dead because the matrix around them has calcified. Capillaries and osteoblasts from the diaphysis penetrate this zone, and the osteoblasts secrete bone tissue on the remaining calcified cartilage.

Thus, the zone of calcified matrix connects the epiphyseal plate to the diaphysis. A bone grows in length when osseous tissue is added to the diaphysis. Bones continue to grow in length until early adulthood. The rate of growth is controlled by hormones, which will be discussed later. When the chondrocytes in the epiphyseal plate cease their proliferation and bone replaces the cartilage, longitudinal growth stops. All that remains of the epiphyseal plate is the epiphyseal line Figure.

How Bones Grow in Diameter While bones are increasing in length, they are also increasing in diameter; growth in diameter can continue even after longitudinal growth ceases.

This is called appositional growth. Osteoclasts resorb old bone that lines the medullary cavity, while osteoblasts, via intramembranous ossification, produce new bone tissue beneath the periosteum. The erosion of old bone along the medullary cavity and the deposition of new bone beneath the periosteum not only increase the diameter of the diaphysis but also increase the diameter of the medullary cavity. This process is called modeling. The process in which matrix is resorbed on one surface of a bone and deposited on another is known as bone modeling.

However, in adult life, bone undergoes remodeling , in which resorption of old or damaged bone takes place on the same surface where osteoblasts lay new bone to replace that which is resorbed. Injury, exercise, and other activities lead to remodeling. Those influences are discussed later in the chapter, but even without injury or exercise, about 5 to 10 percent of the skeleton is remodeled annually just by destroying old bone and renewing it with fresh bone.

Skeletal System Osteogenesis imperfecta OI is a genetic disease in which bones do not form properly and therefore are fragile and break easily.

It is also called brittle bone disease. The disease is present from birth and affects a person throughout life. The severity of the disease can range from mild to severe. Those with the most severe forms of the disease sustain many more fractures than those with a mild form. Frequent and multiple fractures typically lead to bone deformities and short stature. Bowing of the long bones and curvature of the spine are also common in people afflicted with OI.

Curvature of the spine makes breathing difficult because the lungs are compressed. Because collagen is such an important structural protein in many parts of the body, people with OI may also experience fragile skin, weak muscles, loose joints, easy bruising, frequent nosebleeds, brittle teeth, blue sclera, and hearing loss.

There is no known cure for OI. Treatment focuses on helping the person retain as much independence as possible while minimizing fractures and maximizing mobility. Toward that end, safe exercises, like swimming, in which the body is less likely to experience collisions or compressive forces, are recommended.

Braces to support legs, ankles, knees, and wrists are used as needed. Canes, walkers, or wheelchairs can also help compensate for weaknesses. When bones do break, casts, splints, or wraps are used. In some cases, metal rods may be surgically implanted into the long bones of the arms and legs. Research is currently being conducted on using bisphosphonates to treat OI. Smoking and being overweight are especially risky in people with OI, since smoking is known to weaken bones, and extra body weight puts additional stress on the bones.

In intramembranous ossification, the bone tissue is directly laid on a primitive connective tissue referred to as mesenchyma without the involvement of an intermediate cartilage.

This is the difference between endochondral ossification and intramembranous ossification. You can download PDF version of this article and use it for offline purposes as per citation note.

Accessed 7 Sept. Mackie, E J, et al. National Library of Medicine, Available here. Jun 19, CC BY 3. Samanthi Udayangani holds a B. Degree in Plant Science, M. Your email address will not be published. Figure Endochondral Ossification.

Figure Intramembranous Ossification. Leave a Reply Cancel reply Your email address will not be published. Endochondral Ossification vs Intramembranous Ossification. Endochondral ossification is an essential process for the formation of long bones femur and flat and irregular bones such as ribs and vertebrae. This penetration initiates the transformation of the perichondrium into the bone-producing periosteum.

Here, the osteoblasts form a periosteal collar of compact bone around the cartilage of the diaphysis. By the second or third month of fetal life, bone cell development and ossification ramps up and creates the primary ossification center , a region deep in the periosteal collar where ossification begins [link] c.

By the time the fetal skeleton is fully formed, cartilage only remains at the joint surface as articular cartilage and between the diaphysis and epiphysis as the epiphyseal plate, the latter of which is responsible for the longitudinal growth of bones.

After birth, this same sequence of events matrix mineralization, death of chondrocytes, invasion of blood vessels from the periosteum, and seeding with osteogenic cells that become osteoblasts occurs in the epiphyseal regions, and each of these centers of activity is referred to as a secondary ossification center [link] e.

The epiphyseal plate is the area of growth in a long bone. It is a layer of hyaline cartilage where ossification occurs in immature bones. On the epiphyseal side of the epiphyseal plate, cartilage is formed. On the diaphyseal side, cartilage is ossified, and the diaphysis grows in length. The epiphyseal plate is composed of four zones of cells and activity [link]. The reserve zone is the region closest to the epiphyseal end of the plate and contains small chondrocytes within the matrix.

These chondrocytes do not participate in bone growth but secure the epiphyseal plate to the osseous tissue of the epiphysis. The proliferative zone is the next layer toward the diaphysis and contains stacks of slightly larger chondrocytes. It makes new chondrocytes via mitosis to replace those that die at the diaphyseal end of the plate.

Chondrocytes in the next layer, the zone of maturation and hypertrophy , are older and larger than those in the proliferative zone. The more mature cells are situated closer to the diaphyseal end of the plate. The longitudinal growth of bone is a result of cellular division in the proliferative zone and the maturation of cells in the zone of maturation and hypertrophy.

Most of the chondrocytes in the zone of calcified matrix , the zone closest to the diaphysis, are dead because the matrix around them has calcified. Capillaries and osteoblasts from the diaphysis penetrate this zone, and the osteoblasts secrete bone tissue on the remaining calcified cartilage. Thus, the zone of calcified matrix connects the epiphyseal plate to the diaphysis. A bone grows in length when osseous tissue is added to the diaphysis.

Bones continue to grow in length until early adulthood. The rate of growth is controlled by hormones, which will be discussed later. When the chondrocytes in the epiphyseal plate cease their proliferation and bone replaces the cartilage, longitudinal growth stops.

All that remains of the epiphyseal plate is the epiphyseal line [link]. How Bones Grow in Diameter While bones are increasing in length, they are also increasing in diameter; growth in diameter can continue even after longitudinal growth ceases.

This is called appositional growth. Osteoclasts resorb old bone that lines the medullary cavity, while osteoblasts, via intramembranous ossification, produce new bone tissue beneath the periosteum. The erosion of old bone along the medullary cavity and the deposition of new bone beneath the periosteum not only increase the diameter of the diaphysis but also increase the diameter of the medullary cavity. This process is called modeling. The process in which matrix is resorbed on one surface of a bone and deposited on another is known as bone modeling.

However, in adult life, bone undergoes remodeling , in which resorption of old or damaged bone takes place on the same surface where osteoblasts lay new bone to replace that which is resorbed. Injury, exercise, and other activities lead to remodeling. Those influences are discussed later in the chapter, but even without injury or exercise, about 5 to 10 percent of the skeleton is remodeled annually just by destroying old bone and renewing it with fresh bone.

Skeletal System Osteogenesis imperfecta OI is a genetic disease in which bones do not form properly and therefore are fragile and break easily.

It is also called brittle bone disease.