Light and Electron Microscopic Study on the Spleen of Adult Albino Rabbit with Special Reference to the Role of Reticular Cells

Introduction: Despite new information concerning functional morphology of the spleen, there are still some inaccuracies regarding certain points. Aim of the Work: The aim of the present study was to analyze the nature of lymphoid and non lymphoid cellular component occurring in distinct histological compartments of the spleen of the adult albino rabbit. Materials and Methods: Twenty adult albino rabbits were used. Their spleen was processed and subjected to light and electron microscopic examination. Results: The spleen was covered with capsule formed of dense fibroelastic connective tissue contains myofibroblasts. The capsule was covered with mesothelial cells of the covering peritoneum. Reticular fibers extended from the capsule and trabeculae and formed well developed reticular network in the white pulp and marginal zone of the spleen. Reticular cells showed many cytoplasmic processes in relation to lymphocytes and macrophages. These processes were enveloped by basal lamina which was close contact to basal lamina of splenic capillaries. The parenchyma of the spleen was formed of prominent white pulps and red pulps. The white pulp formed of lymphatic nodules and central arteriole. The region between the red and white pulps was called the marginal zone. The marginal zone contained blood sinusoids, lymphocytes, plasma cells, macrophages and red blood cells. The red pulp was formed of splenic cords and blood sinusoids. Two types of macrophages were present. In the red pulp, scavenger macrophages contained large heterophagosomes and lysosomes while, in the marginal zone small non scavenger macrophages were seen. Dendritic cells were present in the marginal zone and had many processes. The nucleus was irregular and eccentric. The cytoplasm of these cells was full of cytoplasmic organelles and electron dens granules. The vasculature of the spleen consisted of the central arteriole in the white pulp and sheathed capillaries and blood sinusoids in the red pulp. Conclusion: Stromal cells of the spleen had a great role on establishing the environment in which immune reaction take place.