Bone marrow is the tissue comprising the center of large bones. It is the place where new blood cells are produced. Bone marrow contains two types of stem cells: hemopoietic (which can produce blood cells) and stromal (which can produce fat, cartilage and bone). Stromal stem cells have the capability to differentiate into many kinds of tissues, such as nervous tissue. Hemaopoietic stem cells give rise to the three classes of blood cell that are found in the circulation: leukocytes, red blood cells (erythrocytes), and platelets (thrombocytes).
"Long bones" are tubular in structure, and the hollow middle is filled with yellow marrow. While the majority of long bones are formed of cortical ("compact") material; at the ends are the epiphysis, which are generally composed of cancellous ("spongy") material and red marrow.
Bone marrow as a food
Bone marrow has fallen out of favor as a food, commonly now being used only as a flavoring for soup. Bone marrow is a source of protein and high in monounsaturated fats. These fats are known to decrease LDLcholesterol levels. Some believe this results in a reduced risk of coronary heart disease, prompting them to make bone marrow a dietary staple. The lack of heart disease and obesity in our hominid ancestors has been credited to their regular consumption of bone marrow. It has also been credited to the fact that they were physically active and died at a young age of other causes. The actual health effects of the addition of bone marrow to the diet is unknown.
Red to yellow marrow conversion may be diffuse or may occur in the form of isolated or confluent islands of fatty marrow (Fig 2).
In patients with polycythemia vera, the bonemarrow of the axial skeleton is diffusely and homogeneously hypointense on T1-weighted MR images and it is indistinguishable from the diffuse marrow abnormality observed in patients with leukemia or myeloma.
MR imaging of the marrow is a useful adjunct to bonemarrow biopsy for patients who are candidates for bonemarrow transplantation and, in particular, for patients with lymphoma, a disease with a well-known patchy mode of infiltration of the bonemarrow.
The importance of the redbonemarrow in physiological economy is indicated by the fact that this is one of the last of the tissues of the body to lose its blood supply as a result of bleeding or of any other cause of anemia.
The marrow is seriously affected by vertebral and costal lesions which affect the innervation of the blood vessels and the cells of the hematopoietic tissues.
The sensory nerves are distributed chiefly to the periosteum and to the region of the redbonemarrow nearest the bony walls.
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