Читать книгу Immunology - Richard Coico - Страница 59

1 E. Neutrophils are derived from myeloid progenitor cells in the bone marrow.

2 C. Terminal differentiation of B cells into plasma cells occurs only in secondary lymphoid organs, such as the spleen and lymph nodes. Circulation of lymphocytes and cellular proliferation (but not antigen‐dependent responses of terminal differentiation) also take place in the primary lymphoid organs, such as the bursa of Fabricius, or its equivalent, and the thymus. The bone marrow is the site where pluripotent stem cells differentiate into precursor B and T cells.

3 D. On antigenic stimulation, the germinal centers contain large populations of B lymphocytes undergoing mitosis and plasma cells secreting antibodies. Virgin immunocompetent lymphocytes are developed in the primary lymphoid organs, not in the secondary lymphoid organs, such as the spleen and lymph nodes. Germinal centers do not participate in the removal of damaged erythrocytes, nor are they a source of stem cells; the latter are found in the bone marrow.

4 A. Blood lymphocytes enter the lymph nodes through the afferent lymphatic vessel via postcapillary venules. They leave the lymph nodes through efferent lymphatic vessels, which eventually converge in the thoracic duct. This duct empties into the vena cava, the vessel that returns the blood to the heart, thus providing for the continual recirculation of lymphocytes.