IMMUNOLOGY

Detailed explanation-1: -As maturation proceeds, B-lineage cells move toward the central axis of the marrow cavity (Fig. 7.4). Later stages of maturation become less dependent on contact with stromal cells, and the final stages of development of immature B cells into mature B cells occur in peripheral lymphoid organs such as the spleen.

Detailed explanation-2: -Inside the bone marrow, blood stem cells divide and mature to make new blood cells. During this process, the cells become either lymphocytes (a kind of white blood cell) or other blood-forming cells. These other blood-forming cells mature into red blood cells, white blood cells (other than lymphocytes), or platelets.

Detailed explanation-3: -These studies indicate that IgDhi B cells normally mature contemporaneously in the bone marrow and the spleen. They also formally establish that B cells in the bone marrow can be activated by blood-borne microbes in the absence of all secondary lymphoid organs.

Detailed explanation-4: -Additionally, B cells present antigens (they are also classified as professional antigen-presenting cells (APCs)) and secrete cytokines. In mammals, B cells mature in the bone marrow, which is at the core of most bones.

Detailed explanation-5: -Bone marrow is major organ for the development and maturation of B cells. B cells are generated from HSCs and developed in bone marrow before they egress into peripheral blood to reach peripheral lymphoid organs. Specific cellular niches for B-cell development include CXCL12-expressing cells and IL-7-expressing cells.

Detailed explanation-6: -B cells originate and mature in the red bone marrow, then after release they concentrate in the lymph nodes, respiratory tract, gastrointestinal tract, and spleen, ready for pathogenic invaders. Then upon encounter they will begin to produce plasma cells and memory cells.

Detailed explanation-7: -As they develop, B cells go through 6 stages: They start as common lymphoid progenitor cells, then become early pro-B cells, then late pro-B cells, then large pre-b cells, then small pre-B cells, and finally immature B cells.