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.
A group of white blood cells called lymphocytes plays a key role in the human immune response. Lymphocytes include cells called B-cells and T-cells that are responsible for flagging and fighting infections in healthy individuals.Antigens are substances that elicit the response of T-cells and B-cells in the body.When a T-cell recognizes a specific antigen, it binds to the substance and produces chemicals called cytokines. group of white blood cells called lymphocytes plays a key role in the human immune response. Lymphocytes include cells called B-cells and T-cells that are responsible for flagging and fighting infections in healthy individuals.