Bone marrow (medulla ossium) is the principal organ of hematopoiesis. In infants it is fills the bone marrow cavity and is characterized by red (medulla ossium rubra). After reaching 4-5 years in the diaphysis of long bones red bone marrow is replaced by adipose tissue and acquires a yellow tinge (medulla ossium flava). In the adult human red bone marrow is stored in the epiphysis of long bones, short and flat bones. Its total weight is 1.5 kg.
Red bone marrow myeloid tissue is formed, which contains hematopoietic stem cells. These cells are the progenitors of all blood cells, and with the current fall in the organs of the immune system, where they are differentiable. Part of the stem cell enters the thymus, where they differentiate as T-lymphocytes, that is thimic-dependent. Later they settled in certain parts, called thimic-dependent areas of lymph nodes and spleen. T lymphocytes destroy outdated or malignant cells, and destroy foreign cells, that is, provide a cellular and tissue immunity.
The remainder of stem cells falls to other bodies immune system, where they differentiate the cells involved in humoral immune responses, ie, B-lymphocytes, or bursozavisimye. The name of these cells comes from the names of the birds present bags (bursa) Fabricius, is a collection of lymphatic tissue in the wall of the cloaca. It is assumed that a person has such a bag or can reside in the bone marrow or her group represent lymphoid nodules of the ileum and appendix. B cells are the progenitors of cells that produce antibodies, or immunoglobulins, and settled in areas bursozavisimyh peripheral organs of immune system.
a., aa. — arteria, arteriae (artery, the artery)
lig., ligg. — ligamentum, ligamenta (ligament, the ligaments)
m., mm. — musculus, musculi (muscle, the muscle)
n., nn. — nervus, nervi (nerve, the nerve)
r., rr. — ramus, rami (branch)
s. — seu (or)
v., vv. — vena, venae (vienna)