Primary bone

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Primary bone
Identifiers

Anatomical terms of bone

Primary bone is the first bone tissue that appears in embryonic development and in fracture repair. It is characterized by its random position of collagen fibers. In most places in adults this tissue is replaced by secondary bone tissue except, for example, near the sutures of calvara or tooth sockets. The secondary bones have lower amounts of osteocytes so primary bone is much more easily penetrated by x-ray.

Collagen is the main structural protein in the extracellular space in the various connective tissues in the body. As the main component of connective tissue, it is the most abundant protein in mammals, making 25% to 35% of the whole-body protein content. Collagen consists of amino acids wound together to form triple-helices of elongated fibrils. It is mostly found in fibrous tissues such as tendons, ligaments, and skin.

In anatomy, a suture is a fairly rigid joint between two or more hard elements of an organism, with or without significant overlap of the elements.

Osteocyte

An osteocyte, a star-shaped type of bone cell, is the most commonly found cell in mature bone tissue, and can live as long as the organism itself. The adult human body has about 42 billion of them. Osteocytes do not divide and have an average half life of 25 years. They are derived from osteoprogenitor cells, some of which differentiate into active osteoblasts. Osteoblasts/osteocytes develop in mesenchyme.

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Clinical significance

Primary bone or the primary ossification center is the beginning of the bone building process during the first trimester. Calcificed cartilage is basophilic and new bone being made is more acidophilic. The primary ossification occurs in the diaphysis. In contrast, secondary ossification centers appear later at the epiphyses of the cartilage and develop similarly to the diaphysis. [1]

Cancer

Primary bone cancer is a type of sarcoma, a cancer that originates in bone, muscle, fibrous tissue, blood vessels, fat tissue, as well as some other tissues. [2] Primary bone cancer can arise in any of the 206 bones in the body but is mostly seen to originate the arms and the legs. [3] The most common cases are observed in children and young adults. The following list includes types of primary bone cancer:

Cancer disease of uncontrolled, unregulated and abnormal cell growth

Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal bleeding, prolonged cough, unexplained weight loss and a change in bowel movements. While these symptoms may indicate cancer, they can also have other causes. Over 100 types of cancers affect humans.

Sarcoma cell type cancer that has material basis in abnormally proliferating cells derived from embryonic mesoderm

A sarcoma is a cancer that arises from transformed cells of mesenchymal origin. Connective tissue is a broad term that includes bone, cartilage, fat, muscle, vascular, or hematopoietic tissues, and sarcomas can arise in any of these types of tissues. As a result, there are many subtypes of sarcoma, which are classified based on the specific tissue and type of cell from which the tumor originates. It is important to note that sarcomas are primary connective tissue tumors, meaning that they arise in connective tissues. This is in contrast to secondary connective tissue tumors, which occur when a cancer from elsewhere in the body spreads to the connective tissue. The word sarcoma is derived from the Greek σάρξ sarx meaning "flesh".

Bone rigid organs that constitute part of the endoskeleton of vertebrates

A bone is a rigid organ that constitutes part of the vertebrate skeleton. Bones protect the various organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, and enable mobility. Bones come in a variety of shapes and sizes and have a complex internal and external structure. They are lightweight yet strong and hard, and serve multiple functions.

See also

Related Research Articles

Bone healing Healing from bone injury

Bone healing, or fracture healing, is a proliferative physiological process in which the body facilitates the repair of a bone fracture.

Soft-tissue sarcoma human disease

A soft-tissue sarcoma is a form of sarcoma that develops in connective tissue, though the term is sometimes applied to elements of the soft tissue that are not currently considered connective tissue.

Bone tumor

A bone tumor is a neoplastic growth of tissue in bone. Abnormal growths found in the bone can be either benign (noncancerous) or malignant (cancerous).

Long bone

The long bones are those that are longer than they are wide. They are one of five types of bones: long, short, flat, irregular and sesamoid. Long bones, especially the femur and tibia, are subjected to most of the load during daily activities and they are crucial for skeletal mobility. They grow primarily by elongation of the diaphysis, with an epiphysis at each end of the growing bone. The ends of epiphyses are covered with hyaline cartilage. The longitudinal growth of long bones is a result of endochondral ossification at the epiphyseal plate. Bone growth in length is stimulated by the production of growth hormone (GH), a secretion of the anterior lobe of the pituitary gland.

Diaphysis

The diaphysis is the main or midsection (shaft) of a long bone. It is made up of cortical bone and usually contains bone marrow and adipose tissue (fat).

Chondrosarcoma connective tissue cancer that has material basis in cells derived from transformed cells that produce cartilage

Chondrosarcoma is a cancer composed of cells derived from transformed cells that produce cartilage. Chondrosarcoma is a member of a category of tumors of bone and soft tissue known as sarcomas. About 30% of skeletal system cancers are chondrosarcomas. It is resistant to chemotherapy and radiotherapy. Unlike other primary bone cancers that mainly affect children and adolescents, chondrosarcoma can present at any age. It more often affects the axial skeleton than the appendicular skeleton.

Chondrocyte

Chondrocytes are the only cells found in healthy cartilage. They produce and maintain the cartilaginous matrix, which consists mainly of collagen and proteoglycans. Although the word chondroblast is commonly used to describe an immature chondrocyte, the term is imprecise, since the progenitor of chondrocytes can differentiate into various cell types, including osteoblasts.

Endochondral ossification Replacement ossification wherein bone tissue replaces cartilage.

Endochondral ossification is one of the two essential processes during fetal development of the mammalian skeletal system by which bone tissue is created. Unlike intramembranous ossification, which is the other process by which bone tissue is created, cartilage is present during endochondral ossification. Endochondral ossification is also an essential process during the rudimentary formation of long bones, the growth of the length of long bones, and the natural healing of bone fractures.

Intramembranous ossification is one of the two essential processes during fetal development of the gnathostome skeletal system by which rudimentary bone tissue is created. Intramembranous ossification is also an essential process during the natural healing of bone fractures and the rudimentary formation of bones of the head. Unlike endochondral ossification, which is the other process by which bone tissue is created during fetal development, cartilage is not present during intramembranous ossification.

Metaphysis

The metaphysis is the narrow portion of a long bone between the epiphysis and the diaphysis. It contains the growth plate, the part of the bone that grows during childhood, and as it grows it ossifies near the diaphysis and the epiphyses.

Ossification The formation of bone or of a bony substance, or the conversion of fibrous tissue or of cartilage into bone or a bony substance.

Ossification in bone remodeling is the process of laying down new bone material by cells called osteoblasts. It is synonymous with bone tissue formation. There are two processes resulting in the formation of normal, healthy bone tissue: Intramembranous ossification is the direct laying down of bone into the primitive connective tissue (mesenchyme), while endochondral ossification involves cartilage as a precursor. In fracture healing, endochondral osteogenesis is the most commonly occurring process, for example in fractures of long bones treated by plaster of Paris, whereas fractures treated by open reduction and internal fixation with metal plates, screws, pins, rods and nails may heal by intramembranous osteogenesis.

Chondroblast

Chondroblasts, or perichondrial cells, is the name given to mesenchymal progenitor cells in situ which, from endochondral ossification, will form chondrocytes in the growing cartilage matrix. Another name for them is subchondral cortico-spongious progenitors. They have euchromatic nuclei and stain by basic dyes. These cells are extremely important in Chondrogenesis due to their role in forming both the Chondrocytes and cartilage matrix which will eventually form cartilage. Use of the term is technically inaccurate since mesenchymal progenitors can also technically differentiate into osteoblasts or fat. Chondroblasts are called Chondrocytes when they embed themselves in the cartilage matrix, consisting of proteoglycan and collagen fibers, until they lie in the matrix lacunae. Once they embed themselves into the cartilage matrix, they grow the cartilage matrix by growing more cartilage extracellular matrix rather than by dividing further.

Epiphyseal plate part of a long bone where growth takes place

The epiphyseal plate is a hyaline cartilage plate in the metaphysis at each end of a long bone. It is the part of a long bone where new bone growth takes place; that is, the whole bone is alive, with maintenance remodeling throughout its existing bone tissue, but the growth plate is the place where the long bone grows longer.

Ossification center

The first step in ossification of the cartilage is that the cartilage cells, at the point where ossification is commencing and which is termed as an ossification center, enlarge and arrange themselves in rows.

Cartilaginous joint They are also called as slightly movable joint

Cartilaginous joints are connected entirely by cartilage. Cartilaginous joints allow more movement between bones than a fibrous joint but less than the highly mobile synovial joint. Cartilaginous joints also forms the growth regions of immature long bones and the intervertebral discs of the spinal column.

The following outline is provided as an overview of and topical guide to trauma and orthopaedics:

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