[Jerryade (OP)]

jeremiah asked the Naked Scientists:

Is appendix and tonsil a vestigial organ? Someone told me that it plays a role in the immune system. How true is this?

What do you think?

[chris]

Hi Jeremiah

They are both secondary lymphoid organs where immune cells (lymphocytes) are introduced to antigens (chemical markers) from pathogens (mainly bacteria and viruses) that they need to learn to recognise. Neither are essential for good health because there are just a small part of the body's defence system and there are other tissues that can take on this role if the appendix and tonsils are absent. Without them, however, there may be a small risk of increased susceptibility to certain infections - particularly in the case of the tonsil, which helps to defend against upper respiratory infections.

Chris