[L. vesicula, a little bladder]
1. A small blister-like elevation on the skin containing serous fluid. Vesicles may vary in diameter from a few millimeters to a centimeter. They may be round, transparent, opaque, or dark elevations of the skin, sometimes containing seropurulent or bloody fluid. In sudamina, they result from sweat that cannot escape from the skin; in herpes, they are mounted on an inflammatory base, having no tendency to rupture but associated with burning pain. In herpes zoster, they follow dermatomes. In dermatitis venenata, they result from contact with poison ivy or oak and are accompanied by great itching. They are also seen in dermatitis herpetiformis or multiformis. In impetigo contagiosa, they occur, esp. in children, in discrete form, flat and umbilicated, filled with straw-colored fluid, with no tendency to break. They dry up, forming yellow crusts with little itching. They are also seen in vesicular eczema, molluscum contagiosum, miliaria (prickly heat or heat rash), chickenpox, smallpox, and scabies.
SEE: herpes; SEE: miliaria
2. A membrane-bound container made inside a cell and occasionally released from it.
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