Do lymphocytes reside permanently in lymphoid tissue then move to other part of body?

No, lymphocytes do not reside permanently in lymphoid tissue and then move to other parts of the body. Lymphocytes continuously recirculate between the blood and lymphoid tissues, ensuring that they encounter and respond to antigens wherever they may be in the body.

Here's an overview of lymphocyte recirculation:

1. Naïve lymphocytes (those that have not yet encountered antigens) are produced in the bone marrow and thymus. They then enter the bloodstream.

2. Lymphocytes travel through the blood and enter lymphoid tissues, such as lymph nodes, the spleen, and Peyer's patches in the gut. They scan the lymphoid tissue for antigens that they may recognize.

3. If a lymphocyte recognizes an antigen that it is specific for, it becomes activated and begins to proliferate, forming a clone of antigen-specific lymphocytes.

4. Activated lymphocytes can differentiate into effector cells, such as cytotoxic T cells or antibody-producing B cells, or into memory cells.

5. Effector cells circulate in the blood and lymphoid tissues, seeking out and eliminating infected cells or producing antibodies to neutralize pathogens.

6. Memory cells remain in the lymphoid tissues and provide long-term immunity to specific pathogens. They can rapidly proliferate and differentiate into effector cells upon re-exposure to the same antigen.

So, while lymphocytes can be found in lymphoid tissues, they are not permanently resident there. They continually circulate between the blood and lymphoid tissues, enabling them to survey the entire body for potential threats and mount appropriate immune responses.