Throughout the miles of lymph vessels, there are small round nodes or

glands, packed fill with lymphocytes which are used to filter the lymph.

These structures are made of lymphatic tissue and here the white blood

cells fight infection. That is why sometimes these glands can be felt, for

example in the armpits, in the groin and neck, as the lymph nodes trap

bacteria or viruses that they cannot destroy immediately. The lymph

node may swell and become painful and sore. Some nodes cannot be

felt, for example those in the abdomen, chest and pelvis. Occasionally

the lymph nodes can trap cancer cells that it cannot destroy. The nodes

then become swollen but not necessarily painful. This is why it is so

important to check any swollen lymph node as cancers can develop in

the lymph system.