Spleen microcirculation (English)

The spleen is enclosed by a fibroelastic capsule from which trabeculae extend and divide the parenchyma into sections. The majority of the parenchyma is comprised of red pulp which is organized into splenic cords (of Billroth) which are separated by splenic sinusoids where the blood is filtered from damaged red cells and cellular debris. The white pulp is composed of cylindrical formations of lymphoid tissue around a central artery; it consists of three compartments: a marginal zone, periarterial lymphoid sheath (PALS), and lymphoid nodule(s). In open circulation of the spleen, blood is emptied into the splenic cords via penicillar arterioles where it is filtered as it passes into the splenic sinusoids. In closed circulation however, the capillaries empty directly into the sinusoids.