Distribution of blood-borne particles of two different sizes in rat spleens

Polystyrene microspheres 5 micron in diameter and Indian ink, consisting of particles 0.03 micron in diameter, were injected into the splenic artery in rats. The distribution of the polystyrene microspheres and the ink particles in the spleen were examined microscopically and morphometrically. The polystyrene microspheres appeared mainly in the red pulp, and the Indian ink particles mostly in the marginal zone, which functions as an immunological filter. (No arteries opened into the lymphoid follicles.)