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. Hematopoietic 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 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 lack of heart disease and obesity in the hominid ancestors of humans 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.
Note:This article was originally taken from a Wikipedia article.