Now we will discuss about Difference between primary lymphoid organs and secondary lymphoid organs
What is primary lymphoid organs and secondary lymphoid organs:
Primary lymphoid organs are the main place where lymphocytes are developed and matured. Differentiation of lymphocytes also occurs in primary lymphoid organs. In primary lymphoid organs stem cells decided to be either T lymphocyte or B lymphocyte.
Bone marrow is a primary lymphoid organ where differentiation of B lymphocytes occurs. T lymphocytes are also produced in bone marrow. But after their birth they travel to thymus gland, a lymphoid organ to become mature. In thymus they become mature B lymphocytes.
In secondary lymphoid organs lymphocytes get specialised for specific antigen. In secondary lymphoid organs lymphocytes come in contact with different types of antigen. After interaction with different types of antigen lymphocytes become specific for different types of antigen. Secondary lymphoid organs mainly catch the antigen coming from outside which is harmful for our body.
Secondary lymphoid organs filter tissue fluid to trap the antigen. Spleen, lymph nodes are secondary lymphoid organs. Peter’s patches, tonsils and mucosal associated lymphoid tissue are also secondary lymphoid organs. In our body approximately 160 lymph nodes are present. They are the site for tissue fluid filtration. They are more in number in chest, pelvis, neck region. Secondary lymphoid organs contain B cells and T cells.
Difference between primary lymphoid organs and secondary lymphoid organs:
In primary lymphoid organs lymphocytes get matured, proliferated. But in secondary lymphoid organs mature lymphocytes reside. When required lymphocytes perform their role to destroy foreign microbes in secondary lymphoid organs. Adaptive immune response occurs in secondary lymphoid organs. It is the main difference between primary lymphoid organs and secondary lymphoid organs.
Primary lymphoid organs give the lymphocyte such an environment so that lymphocytes become mature, differentiated and proliferated. On the other hand secondary lymphoid organs give the mature, proliferated and differentiated lymphocyte such an environment so that lymphocytes get specialised for different types of antigen.
Secondary lymphoid organs arrange the meeting between differentiated, matured lymphocytes with the antigen arrived into lymph flow from outside. Secondary lymphoid organs give the chances to get experience about different types of antigen.
It helps the lymphocyte to understand the nature of antigen. As a result lymphocytes become ready to fight with external microbes. So we can say that secondary lymphoid organs increase the number of functional lymphocytes.
In primary lymphoid organs one type of immune system lymphocytes are present. T lymphocyte cells or T lymphocyte cells present in primary lymphoid organs. But in secondary lymphoid organs both types of lymphocyte cells present. Both T lymphocyte and B lymphocyte present in secondary lymphoid organs.
In primary lymphoid organs there is no chance for lymphocyte cells to come in contact with antigen. But in secondary lymphoid organs lymphocytes have the chance to come in contact with the external antigen.
Primary lymphoid organs and secondary lymphoid organs behave differently with the age. With age primary lymphoid organs become less functional. They do not work properly in old age. Atrophy occurs in old age in primary lymphoid organs. But on the other hand secondary lymphoid organs behave completely differently. Size of secondary lymphoid organs increase with time.
| Primary lymphoid organs | Secondary lymphoid organs |
| In this organ of immunity system lymphocytes originate, become mature, become differentiated. | In this organ of immunity system mature lymphocytes trigger adaptive immunity response with external antigen. |
| Produce an environment for maturation, differentiation and proliferation of lymphocytes. | These organs produce an environment for the mature lymphocyte to become functional in the perspective of immune response. |
| Contain one type of lymphocyte, B lymphocyte or T lymphocyte. | Contain both types of lymphocyte, both B lymphocyte and T lymphocyte. |
| Do not come in contact with antigen. | Come contact with an invading antigen. |
| Become less functional with the increase of age. | Increase in size with time. |
Similarly between primary lymphoid organs and secondary lymphoid organs:
There are some similarities between lymphoid organs of primary and secondary in origin.
Both primary and secondary lymphoid organs strengthen our defence mechanism for external enemy microbes. Immune system cells are migrating in nature. But primary lymphoid organs and secondary lymphoid organs give a platform for development, proliferation and get specialised for the immune system cells.
Read More: Function of lymphatic system detailed study
Reference: Difference between primary lymphoid organs and secondary lymphoid organs
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