Histology Practical Write-Up - Lab Report Example

Histology Practical Write-Up Histology Practical Write-Up Introduction The main function of the thymus is the development of T- lymphocytes that later grow to maturity. These cells named T- lymphocytes upon maturity are moved from the thymus to the spleen and lymph nodes via the blood vessels. The T- lymphocytes are the ones that cause immunity that is mediated by cells. This kind of immunity normally entails activation of some of the specific immune cells so as to see they fight the infection (Marek and Dabrowska 1989: 6). T- cells have proteins that are known as the T- cell receptors and are found on the membrane of the T- cell. These receptors have the capability to identify the various kinds of antigens; note that these are the substances that make the immune system to react (Marek and Dabrowska 1989: 15). The spleen plays an important part in the body protection against pathogen invasion. The spleen also serves as the largest body, blood filter since it is an organ in the blood stream. Due to this reason, the spleen helps in the detection of the aberrant, mechanically damaged and senescent cells (Parham 2014: 23). The spleen uniquely combines the adaptive and innate system, thus helps in the in- time reaction of the innate to penetration from the microbial. It also helps in the immune response that is adaptive in nature whereby cells that interact recognize a given antigen in particular. Another role of the spleen is that it implicates the MHC molecules that are brought by the cells that present antigens (Tona and Vasilescu 2008: 256-57). In the components of the immune system, thymus is a primary organ while the spleen is a secondary organ. The primary organs main roles include the production of lymphocyte and differentiation of the same. The role of the secondary organs is to capture the antigens and then process them (Richard and Geoffrey 2015:27). Methods Eosin and Haemotoxylin Staining The four sections of the lymphoid organs, tissue are provided embed in wax. The procedure that follows aims to make sure that: 1. The wax is removed from the tissues, 2. The tissue is infiltrated with water or alcohol and water. 3. The tissue is stained, 4. The tissue is dehydrated, and 5. Developing an amount that is permanent. The slide is placed upwards on the hot plate and left to see the wax melts. The section is placed for 2 minutes in histoclear. Confirmation is made to see that the section is transparent and there is no visible wax. There is no wax left on the section the section. The section is placed for 2 minutes in the absolute alcohol. The section is moved to 70% alcohol solution for 2 minutes. The section is placed in the Ehrilch’s Haemotoxylin for duration of 30 minutes. This stain is regressive thus the tissues are overstained and this is followed by the removal of the excess stains. The slide is removed with a tissue being held underneath sees that the drips of the stain are captured. The tissue is then rinsed for 30 minutes with tap water. The section is bluish purple in color. The slide is placed in the acid alcohol for duration of approximately 4 seconds. This has made the section turn from bluish to reddish. The slide was later placed in Ammoniated alcohol that made it to wiggle and the end product was the section turning blue. The section is later placed in a 90% alcohol solution for approximately 2 minutes, then transferred to the Alcoholic Eosin for another 2 minutes. A cover slip is placed on the histoclear slide tissue piece. One drop of Histomount is placed on the cover slip’s centre and this is followed by rod twirling to ensure there are no bubbles captured. The slide is removed from the histoclear and immediately placed on the cover slip that is prepared in making the Histomount to spread. The excess Histomount is cleared and the slide is turned over to dry. The slide is labeled with the name, tissue and stain used format. The slide has blue stained nuclei and the other components are pinkish and reddish. Results 1. Thymus lobe There are changes in the structure of thymus by age; this process is called involution. During the involution, the tissue of cortical lymphoid is replaced by the adipose tissue. This is accompanied by the changes related to size since the thymic corpuscles grow bigger. Low Magnification: the tissue capsule surrounding is connected along the surface. Septa the connective tissue can be seen extending into the capsule. The vast smaller lobules that make the thymus are also visible. The lobules have a dark staining cortex while the staining of the medulla is pale. There is no medulla penetration of interlobular septa while lobules in medulla appear to be joined together. Some of the septa carry lymphatic cells that are efferent and blood vessels High Magnification: The cortex is made of a layer that is dense with cells that are closely packed. This is due to the thymocytes and T lymphocytes that have developed and matured. The medulla is made of a central mass (eosinophic) which is surrounded by epithelial cells known as Hassalls corpuscles that are arranged concentrically. They look alike with the blood vessels so they may confuse. A Hystological section of lymph node showing the cortex with many follicles Magnification: 450x 380 Diagram of thymic lobe Magnification: 560x 415 2. The Spleen High Resolution: The main visible parts of the spleen are the red and white pulp. The white pulp has lymphoid cells sheath that is around arteriole that is located eccentrically. Periarterial lymphatic sheaths (PALS) form the immediate surroundings of the arteriole. The PALS are surrounded by the PWP (peripheral white pulp) which has B lymphocytes as components. The white pulp periphery is made of an area that is believed to be the antigen trap and starting the main process. The marginal zone is characterized by the presence of macrophages and lymphocytes. The splenic sinusoids and Splenic cords (from Billroth) form the major part of the red pulp. The Billroth’s splenic cords have macrophages, reticular cells, plasma cells, lymphocytes, and erythrocytes. The role of splenic sinusoids is to allow the cells to move out and come in. This is by help of the capillaries that are modified in structure that allows it to have a lumen that is wide and wall spaces. Hystological section of the spleen Magnification: 1280x 960 3. Thymus lobe The healthy tissues in section 1 looks more clear compared to the specimen in place. The resolution seems to be higher. The healthy tissue tends to have packed or squeezed sections or components as opposed to the specimen. The image parts are not easy to identify in the specimen. This may be due to the resolution power of the microscope used. 4. Spleen The healthy tissue in section two seems like more packed with the components compared to the specimen mounted. The components are clearer and there is a distinction between the diagrams as opposed to the specimen. This might be due to the type of stain used and the resolution of the microscope. Discussion Thymus structure: the cortex appears to be darker when stained compared to the medulla. This makes it easy to differentiate the parts when it comes to drawing the parts. These parts were also the most visible parts with the stains making the clear distinction between the two. The cortex has a network (epithelial network) that tends to be branched more finely compared to the medulla case. This enables one to see the difference thus easy to draw. The low resolution image also shows the lobules and the capsula (outer one). These parts are distinct from the cortex since the cortex is darkly stained due to high absorption power. Spleen structure: The capsule is dark stained making it visible despite its thin feature. The trabecula is distinct from both the capsule and red pulp thus visible. The red pulp forms the major portion of the spleen and it is easy to note the uniformity formed by the nodules in it. The image of these parts is not complicated and neither is it hard to draw. According to Ward, Rehge and Morse (2012), the specimen is not of the mice because the cells of both thymus and spleen seem healthy. The T and B cell receptors are also arranged in an orderly manner. This means that there are mature B and T cells at the periphery of the tissues. References Marek P. D. and Dabrowska B. B. (1989) Immunoregulatory role of thymus, U.S: CRC Press. Parham P. (2014) The Immune System. Oxford: Garland Science Richard C. and Geoffrey S. (2015) Immunology: A short course, Canada: John Wiley and Sons Inc. Tona A. and Vasilescu C, (2008) ‘Role of the spleen in immunity. Immunologic consequences of splenectomy,’ Chirurgia (Bucur), Vol. 103, no.3, pp. 255-63 Ward M. J., Rehg J. E and Morse H. C (2012) ‘Differentiation of rodent immune and hematopietic system reactive lesions and neoplaisas, ’ PMC, Vol. 40, no. 3, pp. 425- 434 Read More