Final answer:
Pus is composed of dead leukocytes, dead tissue cells, and fluid that accumulates at the site of an infection.
Step-by-step explanation:
Dead leukocytes, dead tissue cells, and fluid can all accumulate to form pus. Pus is the accumulation of dead pathogens, neutrophils, tissue fluid, and other cells that may have been killed by phagocytes at an infection site. It typically contains a mixture of dead leukocytes (such as neutrophils and eosinophils), dead tissue cells, and a liquid matrix. During the healing and immune process, more macrophages are recruited to the site to clean up the debris left over, and in cases of severe local infections, large numbers of neutrophils are attracted to the site where they phagocytose the pathogens. After their death, their remnants, along with other cellular debris, culminate in the formation of pus.