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Spleen - Anatomy & Physiology (view source)
Revision as of 11:54, 17 July 2008
, 11:54, 17 July 2008→Innervation
===White Pulp===
===White Pulp===
<p>White pulp is organised in relation to the splenic arterioles and consists of discrete lymphoid tissue surrounding a central arteriole. There is a sheath of T-cells directly around the arteriole, the periarteriolar lymphoid sheath (PALS), which is surrounded by a marginal sinus, and then a zone of B-cells and macrophages (the marginal zone). B cell follicles are associated with the marginal zone and expand and develop germinal centres after antigen activation. The marginal sinuses are linked to the red pulp sinuses. </p>
<p>White pulp is organised in relation to the splenic arterioles and consists of discrete lymphoid tissue surrounding a central arteriole. There is a sheath of T-cells directly around the arteriole, the periarteriolar lymphoid sheath (PALS), which is surrounded by a marginal sinus, and then a zone of B-cells and macrophages (the marginal zone). B cell follicles are associated with the marginal zone and expand and develop germinal centres after antigen activation. The marginal sinuses are linked to the red pulp sinuses. </p>
===Vasculature===
The splenic artery, a branch of the celiac artery, supplies the spleen. The artery branches into arterioles and capillaries, which may either:
*Connect with the venous sinuses, or
*Terminate with open ends in the splenic cords.
Blood released into the splenic cords, either from the sinuses or capillaries eventually filters back into the sinus network. The sinuses converge and empty into trabecular veins, which then merge into a single splenic vein which then empties into the portal vein.
Lymphocytes in the arterial blood migrate from the red pulp sinuses, through the splenic cords and through the white pulp. T cells specifically migrate through the PALS and B cells specifically migrate through the follicles. Antigen in the blood is filtered by the large numbers of macrophages in the splenic cords and white pulp.
====Species Differences====
The splenic artery:
*Passes through the spleen without dividing in ruminants
*Branches regularly as it passes through the spleen in horses and pigs
*Branches before it reaches the spleen in dogs and cats
===Innervation===
===Innervation===
===Lymphatics===
===Lymphatics===
===Histology===
===Histology===