Thymus and Spleen

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Thymus and Spleen. The Spleen: What is it good for?. Filters blood Iron Retrieval RBC reserve Immune Response* Fetal Hematopoiesis. The ‘White’ Pulp. Appears basophilic on H&E and red on silver stain Site where immune response is mounted; formation of germinal centers - PowerPoint PPT Presentation

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  • Thymus and Spleen

  • The Spleen: What is it good for?Filters bloodIron RetrievalRBC reserveImmune Response*Fetal Hematopoiesis

  • The White PulpAppears basophilic on H&E and red on silver stainSite where immune response is mounted; formation of germinal centersGerminal centers with B cells and B cell derivatives push the central artery off to the side

  • White Pulp Vasculature The central artery is found in the white pulpThe central artery is surrounded by the PALS, which is T cellsPenicilli branch from the central artery into the red pulp

  • White Pulp Vasculature The central artery is found in the white pulpThe central artery is surrounded by the PALS, which is T cellsPenicilli branch from the central artery into the red pulp

  • White Pulp Vasculature The central artery is found in the white pulpThe central artery is surrounded by the PALS, which is T cellsPenicilli branch from the central artery into the red pulp

  • Red Pulp Vasculature: Penicilli give rise to ellipsoidsEllipsoids are capillaries ensheathed by reticular cells and macrophages; their lumens are often occluded in histo sectionsBlood is filtered by macrophages through fenestrations in the sinusoids

  • Sinusoids See how the basal lamina is interrupted; evident with both stains

  • Sinusoids Lining of endothelial cells: apposed to one another, but remain separatedMacrophages extend their processes into the lumen of the sinusoid (you can see the remains of RBCs in macrophages)

  • The Red PulpAppears Red on H&EComposed of sinusoids and Cords of BillrothThe cords are the parenchyma of the red pulp; they are composed of reticular tissue w/ macrophages, red blood cells, and lymphocytes

  • Silver Stain*Notice how reticular fibers are evident with silver stain and not H&E*Notice the difference in appearance with the two different stains