Write a note on lymphoid organs.
These are the organs where origin and /or maturation and proliferation of lymphocytes occur.
The primary lymphoid organs are bone marrow and thymus where immature lymphocytes differentiate into antigen sensitive lymphocytes.
After maturation the lymphocytes migrate to secondary lymphoid organs like spleen, lymph nodes, tonsils, Peyer's patches of small intestine and appendix.
The secondary lymphoid organs provide the sites for interaction of lymphocytes with the antigen, which then proliferate to become effector cells.
In higher vertebrates, the immune system can distinguish selfcells and non-self. If this property is lost due to genetic abnormality and it attacks selfcells, then it leads to
Grafted kidney may be rejected in a patient due to
Name the primary and secondary lymphoid organs.
Assertion $(A)$ : Antigen can be easily recognized because it has antigenic determinants.
Reason $(R)$ : The recognition ability is innate.
Why is mother's milk considered the most appropriate food for a new born infant ?