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Transcript
Granulocytes They are non- granular and referred to as mononuclear leukocytes. They contain the specific granules, but frequently contain azurphilic granules (stain with azure dyes). Which are characterisly for lysosomes (primary) Monocytes % of total leukocytes 3 – 8% Origin = monoblast Diameter = 9 - 15 = the largest cell of WBC Nucleus: it is large indented nucleus (kidney or horseshoe shaped) The indentation here is prominent than in lymphocytes. EM = the indentation contain mainly Golgi and centrioles. Stain usually less compact than lymphocyte. Cytoplasmic granules Contains small number of azurphilic granules that contain Hydrolytic enzymes. Functional consideration 1- They are highly phagocytic cells. They are transiently found in the circulation. 2- They differentiate in connective tissues to macrophages. which are highly mobile and exhibit? Pseudopodia their name in different connective tissues are: 1- in C. T Histocytes 2- in liver Cupffer cells 3- in lung Alveolar macrophages macrophayse in spleen, lymphrod and bone marrow At the site of inflammation monocyte leave the circulation C.T and now called macrophages that participate in phagocytosis of bacteria and tissue debris. It concentrated antigen and presented it to the lymphocytes Monocytes increase in chronic inflammation TB, syphilis, typhus. Lymphocytes: They are concern with immune system. % Of total leukocytes 20 - 40 % Diameter = range from 6 - 18 Mm According to this size, they are dividing into smaller, medium and large. The small lymphocytes formed the most majority 79 % They are 5-8 M medium 10-12 large 14-15 The small lymphocytes represent the mature lymphocytes. Nucleus Small here single, large, spherical, may have slightly indented nucleus. They are intensely stained and surrounded by faint ( blue) rim of cytoplasm due to free ribosome's Hetero chromatic nucleus and occasionally azurphilic granules Medium and large size lymphocytes here relatively voluminous Cytoplasm (small with small rim of cytoplasm, large with wider rim of cytoplasm. Medium and small size lymphocytes present mainly in peripheral blood and lymphoid tissues Large size lymphocytes present in mainly lymphoid tissue and rarely in blood. Functional classification of lymphocytes T &B lymphocytes T cells = T lymphocytes = derived from thymus dependent lymphocyte Constitute 70 % of circulating lymphocytes Here longer live span and involve in cell mediated immunity and increase in chronic infection such as TB, syphilis, viral cancer. Long lived lymphocytes may survive for months or years They are thought to be memory cells. B cells = B lymphocytes = have variable life span first discovered in the bursa of fabrics in bird. It is responsible for production of antibodies humoral immunity B + T lymphocytes are only differentiated by immunohistochomical staining by detecting their surface receptors Three types of T lymphocytes 1- Cytotoxic lymphocyte = killer Tk = Tk recognize other Cells that have foreign antigen (especially) on their surface then release lymphokinase to kill the antigen. Antigen recognize by T. C stimulate Tk to be produced and become synthesized. 2- Helper T lymphocyte (T H) recognizes the antigen or foreign body and help B cell + macrophages to participate in immune reaction 3- Suppress T cells (T s cells) ~ this act to suppress the immune response to normal or self molecule thus suppresses action of T and B cells. T cells participation - graft - rejection B lymphocytes = Antigen recognized by memory or sensitized T cells Stimulate helper cell chemotact and activity of B cells B cell enlarges and differentiates into plasma cells secrete antigen antibody that reacts specifically to original antigen for each antigen special type of antibody either to bacteria or its toxin. NB = Not all the activated B cells will transform into plasma cells Majority will form memory B lymphocytes to respond to antigen if exposed again Platelets They are the smallest formed elements of blood 2 - 4 Mm in length They hare flat bi-convex disk shaped (like lens) They are cytoplamic fragments of megakaryocytes Each megakaryocytes produce 1000 - 5000 platelets In blood smear, they appear as single or in clusters – lifespan about 10 days With LM + EM two regions of cytoplasm are distinguishable a- The center region or zone = granulomere b- The peripheral cytoplasm surrounds by hyalomere EM = contain microtubules and actin filaments. In the granules: 3 types could be seen: 1- α = granules = platelets specific protein such as Fibrinogen and clotting factor 2- Dense granules = contain vasoconstriction, ADP, ATP and calcium. 3-Lysosome. Formation of clot: If there is injury to the endothelium of blood Prothrombin vessels Platelets change its shape and aggregate at the site of injury Platelets adhesion and changing in shape Degranulated and release ADP & serratonin which are potent vasoconstrictor. also ADP formed thrombaxan platelets + thrombin fibrinogen fibrin clotting factor Actin, microtubules + myosin, glycogen also help in clot retraction. Platelets also contain thrombosthein - similar to contractile protein cutomyosin of muscle. During processes of healing plasma protein plasminogen convert into plasmin, which dissolve the blood clot.