<unk>  consists of a thin, protein-rich fluid (historically known as liquor puris) and dead leukocytes from the body's immune response (mostly neutrophils). During infection, macrophages release cytokines, which trigger neutrophils to seek the site of infection by chemotaxis. There, the neutrophils release granules, which destroy the bacteria. The bacteria resist the immune response by releasing toxins called leukocidins. As the neutrophils die off from toxins and old age, they are destroyed by macrophages, forming the viscous<unk> . Bacteria that cause<unk>  are called pyogenic. Although<unk>  is normally of a whitish-yellow hue, changes in the color can be observed under certain circumstances.<unk>  is sometimes green because of the presence of myeloperoxidase, an intensely green antibacterial protein produced by some types of white blood cells. Green, foul-smelling<unk>  is found in certain infections of Pseudomonas aeruginosa. The greenish color is a result of the bacterial pigment pyocyanin that it produces. Amoebic abscesses of the liver produce brownish<unk> , which is described as looking like "anchovy paste".<unk>  from anaerobic infections can more often have a foul odor. In almost all cases when there is a collection of<unk>  in the body, a clinician will try to create an opening to drain it. This principle has been distilled into the famous Latin aphorism "Ubi<unk> , ibi evacua" ("Where there is<unk> , evacuate it"). Some disease processes caused by pyogenic infections are impetigo, osteomyelitis, septic arthritis and necrotizing fasciitis. An abscess is an enclosed collection of<unk> . Duodenoscopy image of hepatopancreatic ampulla with<unk>  exuding from it, indicative of cholangitis
Pus
Callus
Papule
Hair whorl
Crown 
Lockets
Dieuches
Blood blister