B-LYMPHOCYTES
B-lymphocytes are the class of lymphocytes, which are produced in the blood-forming tissue of mammals, or, in birds, in a special lymphoid organ connected with the intestine (bursa of Fabricius). Some of these lymphocytes of the bursa or the lymphoid tissue migrate along the blood current into peripherical lymphoid tissues and become B-lymphocytes. They become morphologically distinguishable from T-lymphocytes only after stimulating by an antigen. Non-stimulated T- and B-cells are small cells (only a little larger than an erythrocyte), in which the nuclei occupy the most part of their volume. Both of them are activated by an antigen, which causes their proliferation and differentiation. Activated B-lymphocytes become antibody producers. The most mature cells of them are plasmatic cells with exceedingly developed rough endoplasmic reticulum. Cavities of the rough endoplasmic reticulum are full of antibody molecules.
This class of lymphocytes is responsible for the antibody immune response.