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1. A device for destroying formations in a body, comprising a tubular member having an axis and introducible into a body to an area of a formation, said tubular member having a front end; gripping means provided at said front end of said tubular member for gripping a formation, said gripping means including a plurality of gripping elements which arranged around said axis in a circumferential direction and are movable between a closed position in which they are arranged without gaps between each other to form a closed space and an open position in which they are spaced from each other; a tube having a smaller diameter than a diameter or said tubular member and extending along said axis inside said tubular member, said tube having a front end connected with said gripping elements of said gripping means, said tube being axially movable inside said tubular member between one position in which it acts on said gripping elements so as to move said gripping elements to said open position and another position in which said tube acts on said gripping elements so as to move said gripping elements to said closed position; and a formation destroying element extending inside said tube and also inside the tubular member and having a front end provided with a working part operative for destroying the formation when said working part is brought in contact with the formation, so that said tube first moves said gripping elements to said open position and said gripping elements surround a formation, and then said tube moves said gripping elements to said closed position and said gripping elements are closed without gaps therebetween to form said closed space, and said formation destroying element is activated so that said working part destroys the formation, the device can be withdrawn from a body with fragments of the formation held inside said closed space formed by said gripping elements in said closed position.