While the tadpoles of competing species may complete metamorphosis in as little as just a few short months, Bullfrog tadpoles can remain in the same state for as long as one to two years before they actually become adult frogs.
Two types of white blood cells called lymphocytes are vital to the specific immune response. Lymphocytes are produced in the bone marrow, and mature into one of several subtypes. The two most common are T cells and B cells. An antigen is a foreign material that triggers a response from T and B cells.
When an antigen enters the body or tries to enter the body, the immune system is triggered. Chemical signals are sent to alert all the different parts of the immune system into action. First, the B cell meets the antigen. The B cell will create the antibody protein and stick it to the antigen.