Explain Neutrophils
They form about 50-70% cells. They have fine dust like particles in the cytoplasm which stain purplish. Tissues, cells damaged by the invading microbes release certain chemicals called chemokines, which attract neutrophils from blood. The neutrophils engulf and digest the microorganisms infecting the body tissues. They are called phagocytes and the process is known as phagocytosis.
To refresh your memory, in the phagocytosis process, the cell membrane of phagocyte invaginates and encloses a bacterium in a vacuole known as phagosome, the vacuole then fuses with lysosome to formphagolysosome. The bacteria are digested by the enzymes present in the lysosome. The doctrine of phagocytosis was advanced by a Russian physiologist, Elie Metchnikov in 1882. He got Nobel Prize for medicine and physiology in 1908. A neutrophil may engulf as many as twenty bacteria before it dies. If new entry of an organism is there, then it is trapped by another phagocytic cell known as the macrophage (big cells which can eat), about which we will learn in a little while from now.