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.
There are thousands of different B cells in our body, each of which produces a unique antibody. T cells develop in the thymus and help coordinate a rapid and tailored immune response to specific infectious organisms. Antibodies are proteins that are secreted from B cells. Antibodies help the immune system recognize foreign proteins that do not belong to the body. In doing so, they initiate an inflammatory response and clear the body of the invader. Neutrophils are the white blood cells that arrive first at the site of injury.