What does a vesicle contain?

A vesicle is a small, fluid-filled sac within the body, often formed as a result of cellular activity or injury. In dermatological terms, a vesicle is typically associated with certain skin conditions and is characterized by its content, which is primarily clear fluid. This clear fluid can be serous, which means it is similar to serum (the liquid part of blood). Vesicles are often seen in conditions such as chickenpox or herpes simplex, where they can appear as blisters on the skin.

The other options describe different types of lesions or contents that do not categorize as vesicles. Pus and debris usually characterize pustules, while air and gas are not typically found in vesicles. Dead skin cells can accumulate in various skin conditions but do not define the vesicular structure itself. Thus, the presence of clear fluid is what specifically identifies a vesicle.