Cerebral microembolization following carotid injection of dextran microspheres in rabbits.

Dextran microspheres (Sephadex G25 fine) from 25 to 105 micrometer, labelled with fluorochrome (Lissamine Rhodamine B), in concentrations of 1 and 2 million particles suspended in 2 ml Ficoll 70, were injected into the right common carotid artery of 10 white female rabbits (Danish domestic variety) which were sacrificed at intervals from 5 min to 10 days after injection. Histopathological study of the brains revealed a number of spheres in arteries and arterioles often occluding pial vessels of both hemispheres (more than 80% in the right hemisphere). Less than 0.5% of microspheres were recovered. No macroscopic and only a few microscopic infarcts were seen. The rabbits surviving until 10 days after injection had no visible neurological disturbances, but all rabbits died immediately or within 5 min after the injection of approximately 2 million particles.