RT Book, Section A1 Mescher, Anthony L. SR Print(0) ID 1160662533 T1 The Immune System & Lymphoid Organs T2 Junqueira’s Basic Histology: Text and Atlas, 15e YR 2018 FD 2018 PB McGraw-Hill Education PP New York, NY SN 9781260026177 LK accessmedicine.mhmedical.com/content.aspx?aid=1160662533 RD 2024/04/24 AB The immune system provides defense or immunity against infectious agents ranging from viruses to multicellular parasites. Histologically this system consists of a large, diverse population of leukocytes located within every tissue of the body and lymphoid organs interconnected only by the blood and lymphatic circulation. Immunity obviously has tremendous medical importance, one part of which focuses on autoimmune diseases in which immune cells begin to function abnormally and attack molecular components of the body’s own organs.