Fig. 9From: Assessment of the toxicity and carcinogenicity of double-walled carbon nanotubes in the rat lung after intratracheal instillation: a two-year studyA shows an SEM image of numerous thin DWCNT fibers (arrow) engulfed by a macrophage. B shows an SEM image of a rigid MWCNT-7 fiber penetrating through the cell membrane of a macrophage (arrow). Free MWCNT-7 fibers were also observed in the alveolar spaceBack to article page