title: Microcirculatory pathways in normal human spleen, demonstrated by scanning electron microscopy of corrosion casts.
abstract: Confusion regarding microcirculatory pathways in normal human spleen has arisen due to extrapolation from pathological material and from other mammalian spleens, not to mention difficulties in tracing intricate three-dimensional routes from the study of thin sections or cut surfaces of tissue. We examined microcirculatory pathways in normal human spleens freshly obtained from organ transplant donors. A modified corrosion casting procedure was used to obtain an open view of vessels and their connections. Our results demonstrate: 1) "arteriolar-capillary bundles" within lymphatic nodules and extensive branching of arterioles in the marginal zone (MZ); 2) the marginal sinus around lymphatic nodules; 3) the peri-marginal cavernous sinus (PMCS) outside the MZ or immediately adjacent to the nodule itself; the PMCS receives flow via ellipsoid sheaths and MZ, or directly from arterial capillaries, and drains into venous sinuses; 4) fast pathways for flow into venous sinuses via ellipsoid sheaths; 5) arterial capillary terminations in the reticular meshwork of the red pulp or MZ ("open" circulation); direct connections to venous sinuses also occur ("closed" circulation), although rarely; and 6) numerous open-ended venous sinuses in the MZ, allowing a large proportion of the splenic inflow to bypass the red cell filtration sites in the reticular meshwork and at venous sinus walls.
authors: Department of Biophysics, University of Western Ontario, London, Canada.
authors: E E
authors: EE
authors: Schmidt
authors: I C
authors: IC
authors: MacDonald
authors: A C
authors: AC
authors: Groom
mesh_terms: D006801:Humans; D008208:Lymphatic System / Q000098:blood supply / Q000166:cytology / Q000648:ultrastructure; D008833:Microcirculation; D008855:Microscopy, Electron, Scanning; D008953:Models, Anatomic; D012157:Mononuclear Phagocyte System / Q000098:blood supply / Q000166:cytology / Q000648:ultrastructure; D013154:Spleen / Q000033:anatomy & histology / Q000098:blood supply* / Q000166:cytology / Q000648:ultrastructure; D014019:Tissue Donors