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Bone marrow is a semi-solid tissue found within the spongy (also known as cancellous) portions of bones. [2] In birds and mammals, bone marrow is the primary site of new blood cell production (or haematopoiesis). [3] It is composed of hematopoietic cells, marrow adipose tissue, and supportive stromal cells.
Functional cells may be lost through necrosis, which is the premature death of cells caused by environmental disturbances, such as diseases or injuries. [3] Functional cells may also need to be replaced after undergoing apoptosis, which is the programmed death of cells that occurs normally as part of an organism's development. [ 3 ]
Bone marrow failure in both children and adults can be either inherited or acquired. Inherited bone marrow failure is often the cause in young children, while older children and adults may acquire the disease later in life. [3] Acquired bone marrow failure may be due to aplastic anemia [4] or myelodysplastic syndrome.
Necrotic bone does not undergo resorption; therefore, it appears relatively more opaque. Attempts at repair of ischaemic-damaged bone will usual occur in 2 phases. First, when dead bone abuts live marrow, capillaries and undifferentiated mesenchymal cells grow into the dead marrow spaces, while macrophages degrade dead cellular and fat debris ...
Upon reperfusion, repair of bone occurs in two phases. First, there is angiogenesis and movement of undifferentiated mesenchymal cells from adjacent living bone tissue grow into the dead marrow spaces, as well as entry of macrophages that degrade dead cellular and fat debris. [2]
Osteomyelitis of the jaws is osteomyelitis (which is infection and inflammation of the bone marrow, sometimes abbreviated to OM) which occurs in the bones of the jaws (i.e. maxilla or the mandible). Historically, osteomyelitis of the jaws was a common complication of odontogenic infection (infections of the teeth). Before the antibiotic era, it ...
When bone marrow develops, it eventually assumes the task of forming most of the blood cells for the entire organism. [3] However, maturation, activation, and some proliferation of lymphoid cells occurs in the spleen, thymus, and lymph nodes. In children, haematopoiesis occurs in the marrow of the long bones such as the femur and tibia.
Dysbaric osteonecrosis or DON is a form of avascular necrosis where there is death of a portion of the bone that is thought to be caused by nitrogen (N 2) embolism (blockage of the blood vessels by a bubble of nitrogen coming out of solution) in divers. [1] Although the definitive pathologic process is poorly understood, there are several ...