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.
Primary response to infection. If a pathogen enters your body, white blood cells of your immune system quickly recognise its foreign antigens. This stimulates specific lymphocytes to grow, multiply and finally produce antibodies that will stick to the antigens on the invading pathogens and destroy them.ymphocyte. A type of white blood cell that make antibodies to fight off infections. Pathogen. A micro-organism that causes disease. Phagocyte. Phagocytes are the white blood cells that protect the body by ingesting harmful foreign particles, bacteria, and dead or dying cells.