Macrophage-sheathed capillaries in spleen (human)

Azan. The branching of each penicillar arteriole gives rise to capillaries and a slow-down of the blood stream. In certain regions monocyte-derived macrophages leave the capillary and enter its wall where they develop into macrophages. Together with the present reticular cells these cell accumulations form a sheath locally around the capillary (1). One of the major functions of this sheath is to get rid of ageing cells and debris from the blood. (2) are open venous sinusoids.