Schematic view of the blood circulation and the structure of the spleen, from the trabecular artery to the trabecular vein. Small branches of these arteries are called central arterioles and become enclosed within a sheath of lymphoid cells, the periarteriolar lymphoid sheath (PALS) in the white pulp. B cells in these sheaths can form nodules as the largest masses of white pulp, and around these nodules are located the marginal zone sinuses. emerging from the white pulp, the central arteriole branches as the penicillar arterioles, which lead to sheathed capillaries. From these, blood flows into either a closed circulation passing directly into splenic sinuses (S) or an open circulation, being dumped from the vasculature into the lymphoid tissue of the red pulp’s splenic cords. From there viable blood cells reenter the vasculature through the walls of the sinuses.
Image Taken from the Junqueiras Basic Histology Text and Atlas 13th.
Splenic Microcirculation is shown in the most easiest way. Splenic Open Circulation and Closed Circulation are shown in Figure from Junqueira’s Histology.