Bone marrow
Bone marrow (or "medulla ossea") 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:
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hematopoietic (which can produce blood cells) give rise to the three classes of blood cell that are found in the circulation:
white blood cells (leukocytes),
red blood cells (erythrocytes), and
platelets (thrombocytes).
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Mesenchymal stem cells are found arrayed around the central sinus in the bone marrow. They have the capability to differentiate into
osteoblasts,
chondrocytes,
myocytes, and many other types of cell. They also function as "gatekeeper" cells of the bone marrow.
The normal bone marrow architecture can be displaced by
malignancies or infections such as
tuberculosis, leading to a decrease in the production of blood cells. In addition, cancers of the hematologic progenitor cells in the bone marrow can arise; these are the
leukemias.
Long bones, like the
femur 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.
Large amounts of red bone marrow can also be found in
flat bones like those of the
ribs,
pelvis and
skull.
Though once used in various preparations, including
pemmican, bone marrow has fallen out of favor as a food. Now, it is commonly used only as a flavoring for soups and sauces, although dishes with intact bone marrow can still be found in some European restaurants. Bone marrow is a source of
protein and high in
monounsaturated fats. These fats are known to decrease
LDL cholesterol levels. Some believe this results in a reduced risk of
coronary heart disease, prompting them to make bone marrow a
dietary staple. The actual health effects of the addition of bone marrow to the diet remain unknown.
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Leukemia*
Bone marrow transplant*
Aplastic anemia*
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