It is composed of cells derived primarily from the myeloid compartment of bone marrow differentiation. More recently, a population of neutrophil-killers has been described to populate peripheral areas of the<unk> . At least three distinct cellular markers can be used to identify cells of the<unk> , MOMA-1, ERTR-9 and MARCO. Blood flow The<unk>  <unk>  is a highly transited area that receives large amounts of blood from the general circulation. Remarkably, the splenic microvasculature shows striking differences in mice and humans. In humans, the spleen receives blood from the splenic artery, which branches into central and penicillar arterioles. Owing to the absence of a histologically defined<unk>  sinus, the blood flowing in penicillar arterioles directly drains into capillaries of the red pulp and perifollicular zone. The perifollicular zone is a well-defined area of decreased resistance that separates the<unk>  from the red pulp. Both the perifollicular zone and the red pulp consist of an open circulatory system of blood-filled spaces known as splenic cords, which have no defined endothelial delimitation and are in close contact with the venous sinusoidal vessels of the red pulp.
Marginal zone
Blue zone
Inner nuclear layer
Watershed area 
Outer nuclear layer
Trigger zone
Episcleral layer
Sommer's sector