Identification of Lymphoid Tissue in Section Thymus, Spleen or Lymph Node - Lab Report Example

HISTOLOGY PRACTICAL WRITE UP HISTOLOGY PRACTICAL WRITE UP Introduction The immune system comprises of several interdependent cells that protect the body collectively from bacteria, fungi, viruses and tumour cells. The cells made up of the immune system rely on the T helper for activation of cytokines, lymphokines and interleukins in the form of secretions. The primary function of the thymus in the immune system is a production of mature T cells. Immature thymocytes that are known as prothymocytes tend to leave the bone marrow and are in the thymus. Through the process of thymic education, beneficial T cells are spared while unwanted T cells that were likely to evoke an injurious autoimmune response are. Upon the maturation of the beneficial T cells, they are released into the blood. The thymus is a primary lymphoid organ (Paul, 2013). The spleen on its part is an immunologic blood filter. The spleen is of T cells, B cells, dendritic cells, natural killer cells, red blood cells and macrophages. The spleens functions by capturing antigens from the blood passing through the spleen. The migratory macrophages together with the dendritic cells transport the foreign bodies to the spleen through the blood stream. When the antigens get to the spleen and gets into contact with the appropriate B or T cells, an immune response is initiated. The B cells once activated produces large amounts of antibody which kills the antigen as well as aged red blood cells. The spleen contains two types of T-cells which are helper T-cells and killer T-cells. The helper T-cells are responsible for systematising the attack while the killer T-cells destroys the infected cell since it has then been turned into a virus reproduction factory. The spleen is a secondary lymphoid organ since it contains both T and B cells and requires an antigen entry to stimulate the lymphoid cells (Turgeon, 2014). Methods The primary aims of this lab experiment are to: 1. Identification of lymphoid tissue in section thymus, spleen or lymph node 2. Identification of T and B cell areas in the lymphoid tissue provided 3. Identification of immunodeficiency as a result of the inability to arrange T and B receptors that lead to the unavailability of mature T and B cells in the periphery. Through the use of 4 tissue sections of lymphoid organs the process will involve: 1. Infiltration of the tissues with a mixture of water and alcohol 2. Staining of the tissues 3. Dehydrating the tissues 4. Making a permanent mount. Since the tissue sections are in wax, they are placed in hot plates for 2 minutes till all the wax is melted, and no traces of wax found in the tissues. Within a two-minute interval, the tissues are placed in absolute alcohol, 90% alcohol and 70% alcohol. In order to stain the tissues, they are placed in Ehrlich’s Haematoxylin for 45 minutes. Since this is a regressive stain, over stained tissues will have the stain solution removed with a tissue paper and rinsed for 30 minutes with tap water. The tissues should appear bluish purple/dark blue. The tissues are in acidic alcohol for 4 minutes and turn red. Immediately the slides are put into ammoniated alcohol and will turn blue. Within two-minute duration, the tissue slides are placed into 70% alcohol, 90% alcohol and alcoholic Eosin. A slide is placed again into 90% alcohol for 30 seconds then absolute alcohol for a minute. Another slide is into Histoclear for 2 minutes and covered with a coverslip. 4-5mm of Histamount is and allowed to spread then a label added. The cell nuclei should be stained blue with other cellular components stained various shades of pink and red (Paul, 2013). Results The figures below are the fully labelled diagrams made of the sections 1-4. These images have been magnified to X12 magnification. Exterior view of the Spleen 1. Transverse drawing of the spleen (5 um) 2. Longitudinal section of the thymus 3. Section four For sections 1-2, the spleen is composed of both red and white pulp. The white pulp produces and develops immune cells and red blood cells while the red pulp is responsible for blood purification and removal of aged or dead cells. Blood gets into the spleen at the hilus via the splenic artery. The splenic artery divides into trabecular arteries found in the trabecular. Arterioles from the trabecular get into the red pulp and are surrounded by the lymphoid tissue. The red pulp is of networked of splenic cords and venous sinuses. The splenic cords comprise of reticular fibers, reticular cells, and associated macrophages. The macrophages are phagocytic thus remove old and damaged erythrocytes and blood-borne particulate matter ­ (Turgeon, & Turgeon, 2014). The spleen the Macrophages play an active role in the regulation of the immune responses. Their role is detection and ingestion of foreign materials that are to the T-cells and B-cells as antigens. Induced macrophages exhibit an increased amount of phagocytosis and secretion (Paul, 2013). The primary difference between the two organs is the coloration of both cells. While in sections 1-2 the organs have bright pink colouration, in sections 3 and 4 have organs have pale reddish colouration. Secondly the organs in sections 1 and 2 have a more turgid and active texture while organs in sections 3 and 4 have a less turgid and shrunk texture. Finally, the organelles in section 1-2 are easily stained while those in 3-4 require too much solution and time to stain (Paul, 2013). Discussion The tissues are said to be the spleen and the thymus respective from their respective reactions with the different alcoholic, acid, and alcoholic Eosin respectively. This is because of the different cytokine reactions found in both T-cells and B-cells to the different acidic or base solutions. When placed in an acidic solution, both T and B cells are denatured hence turn red. The various shades of pink and red are also as a result of the difference in the amounts of cytokine in the organs (Turgeon, & Turgeon, 2014). The organs used in this section could not have been derived from mice since it is larger in shape than the average size of mouse organs. Furthermore, mice have low-level immune response hence the different reactions would not have been experienced as a result of high-level cytokine secretions. On the other hand, mice have very high immunodeficiency levels thus the cytokine secreted is very low. In the case of the above reaction, mouse lymphoid organs would not have exhibited active variation in the tissue colour from red to dark blue. Finally, a mouse spleen has a slight blue colouration as a result of increased extramedullary haematopoiesis that is not available in the above organelles ­ (Turgeon, & Turgeon, 2014). Reference List Paul, W. E. (2013). Fundamental immunology. Philadelphia, Wolters Kluwer Health/Lippincott Williams & Wilkins Turgeon, M. L., & Turgeon, M. L. (2014). Immunology & serology in laboratory medicine.St. Louis, Mo, Elsevier/Mosby. Read More