Bursa equivalent

Leukocytes are derived from stem cells in the bone marrow. These cells become functionally mature cells granulocytes, lymphocytes, and macrophages. Lymphocytes divided into T cells (thymus derived) and B cells (bursa equivalent), depending on the site of maturation. 

The immunocytes are all involved in specific types of immune response that are generally divided into two types (1) cell-mediated, i.e., specifically sensitized T cells (derived from the thymus) which are associated with graft rejection, resistance to certain viruses, bacteria, fungi, and protozoa, and delayed-type hypersensitivity and (2) humoral-mediated, i.e., B cells (bursa equivalent) which produce specific antibodies after the body is exposed to a specific antigen. 

The 12% of lymphoma and 10% of chronic lymphatic leukemia with paraproteins may actually represent neoplasia of the B-lymphocyte line (bursa-equivalent), i.e., true plasma cell precursors. The prognosis... 

There are two main types of immune response cell-mediated and humoral. Cell-mediated immunity involves specifically sensitized thymus-dependent lymphocytes. Humoral immunity involves the production of antibodies (immunoglobulins) from bursa equivalent lymphocytes or plasma cells. The mechanisms will be discussed in more detail below. 

Immunologically reactive or immunocompetent cells are lymphocytes which, together with granulocytes and erythrocytes, originate from common hemopoietic stem cells (Wu et al. 1967). The sites of primary lymphopoiesis are the bursa of Fabricius (in birds) and the thymus in mammals no bursa has been found but an equivalent organ is inferred (Mitchell and Miller 1968 Perey et al. 1968 Owen and Ritter 1969). Lymphocytes which differentiate within the thymus independent of antigenic influence become thymus-derived or thymus-processed lymphocytes, so-called T-cells. It is now generally accepted that a cooperation between T-cells and bursa-equivalent lymphocytes (B-cells) is necessary for induction of IgM... 

The other type of immunity called humoral immunity originates from stem cells processed by a bursa-equivalent in mammals. As a result plasma cells will secrete specific immunoglobulins. This route of defense is involved in protection against some bacteria and viruses and is responsible for immediate-type hypersensitivity reactions. 

Site of differentiation Bursa of Fabricius (in birds) as yet unknown equivalent in mammals Thymus... 

Parameters B-lymphocytes (from bursa of Fabridus in birds or bursal equivalent ) T-lymphocytes (from thymus)... 

Figure 5. Effect of injection of 1 female equivalent (FE) of brain-subesophageal ganglion homogenate containing PBAN along with various amounts of bursa homogenate (FE) on the amount of Z11-16 AL present in gland extracts of virgin 3-day-old females of H. zea. Extracts were obtained 1 h after injection of 30 1 of test substances and analyzed for the titer of Z11-16 AL by capillary gas chromatography as in Figure 1 (n-5 each treatment).

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