Final answer:
Neutrophils are granulocytes and form the most prominent part of leukocytes, playing a crucial role in the body's nonspecific immune response. They are larger than red blood cells and have a lobed nucleus, with their granules containing materials that combat infection.
Step-by-step explanation:
Neutrophils are a type of white blood cell, also referred to as leukocytes. They are characterized as granulocytes due to the presence of granules in their cytoplasm that can be stained with neutral dyes. These cells are essential components of the immune system, usually measuring between 10-12 µm in diameter, making them larger than red blood cells (erythrocytes). Neutrophils account for 50-70 percent of the total leukocyte count and have a key role in providing an early, rapid, and nonspecific defense against invading pathogens. Their nucleus is lobed, typically with two to five lobes that increase in number as the cell ages, earning mature neutrophils the name 'polymorphonuclear' or 'polys.' In contrast, immature neutrophils, known as 'bands,' have fewer lobes.
Upon encountering infection, neutrophils are attracted to and move towards the affected tissues by a process called chemotaxis. Their granules contain various substances that aid in the defense mechanisms, including enzymes and other vasoactive mediators such as histamine. Unlike macrophages, which are agranulocytes (having few or no cytoplasmic granules), neutrophils actively consume and neutralize pathogens through phagocytosis, further contributing to the body's immune response.