Platelet Production, Structure, and Function PDF

[TRANS] LESSON 1: PLATELET PRODUCTION, STRUCTURE, AND FUNCTION PRODUCTION: MEGAKARYOCYTOPOIESIS Megakaryocytopoiesis – production and development of megakaryocytes. o Progenitor: CMP or CFU-GEMM o Lineage: Megakaryocyte-Erythrocyte Progenitor o Site: Bone Marrow (Specificall...

[TRANS] LESSON 1: PLATELET PRODUCTION, STRUCTURE, AND FUNCTION PRODUCTION: MEGAKARYOCYTOPOIESIS Megakaryocytopoiesis – production and development of megakaryocytes. o Progenitor: CMP or CFU-GEMM o Lineage: Megakaryocyte-Erythrocyte Progenitor o Site: Bone Marrow (Specifically Red Bone Marrow) Megakaryoblasts – develops into the megakaryocyte, which then give rise to the blood platelet/thrombocyte. o It is the first identifiable stage. Flow Cytometry – is the identification test for the progenitors. Megakaryocytes – are the largest cells in the bone marrow THREE STAGES OF MEGAKARYOCYTE and possess multiple chromosome copies (polyploid). PROGENITORS Platelets arise from unique bone marrow cells called megakaryocytes. Thrombopoietin (TPO) – hormone that trigger megakaryocytopoiesis. It is produced by the liver. Figure: Megakaryoblast BFU-Meg – clones hundreds of daughter cells through HEMATOPOIETIC STEM CELLS (CD34) mitosis. CFU-Meg – clones dozens of daughter cells through mitosis. LD-CFU-Meg – undergoes the first stage of endomitosis. o LD stands for Low Density o Endomitosis – a form of mitosis unique to megakaryocytes in which DNA replication and cytoplasmic maturation are normal, but cells lose their capacity to divide. o At this point, there is a need to stop the production of platelet because it is reach the demand. ENDOMITOSIS Endomitosis is a form of mitosis that lacks telophase and cytokinesis (separation into daughter cells). TRANSCRIPTION GENE PRODUCTS: o GATA-1 (Globin Transcription Factor – 1) – MEGAKARYOCYTE PROGENITORS regulated by cofactor FOG-1 (inducer – promotes endomitosis). ▪ A product of X chromosome gene. o FOG1 (Friend of GATA) – product of ZFPM1 (Zinc Finger Protein Multitype 1) (inducer) o MYB (inhibitor) – shut down endomitosis. GATA-1 and FOG1 transcription slows (initiate) → RUN X1 (gene) mediates the switch from mitosis to endomitosis by suppressing the Rho/ROCK signaling pathway (a part of pathway in chemotherapy) → suppressed assembly of actin cytoskeleton → inadequate actin and myosin assembly in cytoplasmic constrictions (where separation occurs) → ENDOMITOSIS. V.T. BERNARDINO, K.D. JUDAL, A.J. MANGILIT, E.J. SABERON, M.S. SOLMERON, S.C. TUMAGAY, N.T. VELASCO | BSMT 1  TRANS: PLATELET PRODUCTION, STRUCTURE, AND FUNCTION MEGAKARYOCYTE PROGENITORS QUESTION IN BOARDS AND ADDITIONAL NOTE ⚫ Megakaryocyte-Erythrocyte progenitors → differentiates to ⚫ Question: In flowcytometry, positive with MPL, CD34 but megakaryocyte through thrombopoietin (TPO) and some negative with CD41. What is this progenitor? cytokines. ANSWER: Burst-Forming Unit - Megakaryocyte (BFU- ⚫ 3 Megakaryocyte lineage progenitor cells: BFU-Meg, CFU- Meg) Meg, LD-CFU-Meg) ⚫ Myeloperoxidase (-) and Sudan Black B (-) - Initially o BFU-Meg and CFU-Meg → participate in normal and myeloid. Positive of CD41 meaning it is megakaryoblast undergo mitosis to maintain a pool of megakaryocyte progenitors. HORMONES AND CYTOKINES FOR o LD-CFU-Meg → Less proliferative because it only MEGAKARYOPOIESIS undergo endomitosis. ⚫ Hormone - Thrombopoietin ⚫ Megakaryocyte progenitors leave the proliferative stage ⚫ Cytokines - IL-3, IL-6, IL-11 and enter terminal differentiation. ⚫ Interleukin-3 will help thrombopoietin in the early stages of ⚫ Megakaryocyte progenitors can’t be differentiated through megakaryocytopoiesis. the help of microscope. It is always in the process of ⚫ In the later stages, we need Interleukin-6, and Interleukin- flowcytometry. 11. ⚫ In terminal differentiation, we can now differentiate immature megakaryocyte with the use of microscope. THROMBOPOIETIN ⚫ NOTE: BFU-Meg, CFU-Meg, and LD-CFU-Meg, if we check them under the microscope for example if we ⚫ Induce stem cell differentiation aspirate bone marrow, it resembles lymphocytes. ⚫ Induce proliferation and platelet release 1. BFU-Meg (Burst Forming Unit - Megakaryocyte) - least ⚫ Found in kidney, liver (main poduction of TPO occurs mature. here), stromal cells and smooth muscles. 2. CFU-Meg (Colony Forming Unit - Megakaryocyte) - *Diploid, ⚫ Circulates in the plasma participate in normal mitosis ⚫ mRNA for TPO has been found in kidney, liver, and smooth 3. LD-CFU-Meg (Light Density - Colony Forming Unit - muscles. Megakaryocyte) - loses its capacity to divide but it retains ⚫ Recombinant TPO (synthetic TPO mimetics) - synthetic DNA replication and cytoplasmic maturation. agent/ therapeutic agents in cases that body is unable to ⚫ NOTE: All 3 resembles lymphocytes in BM smear produce TPO or disease in liver. IMMUNOLOGIC TEST (FLOWCYTOMETRY) INTERLEUKIN-3 (IL-3) ⚫ In the early stages of megakaryocytopoiesis, it acts in synergy with TPO to induce early differentiation. ⚫ TPO cannot stand alone that is why it needs IL-3. INTERLEUKIN-6 & INTERLEUKIN-11 (IL-6 & IL-11) ⚫ Enhance the later phenomena of endomitosis, megakaryocyte maturation, and platelet release. ⚫ In LD-CFU-Meg, this is the stage where IL-6 & IL-11 begins to help ⚫ They also help in maturation of megakaryoblast ⚫ If the patient is suffering from purpura, or thrombocytopenia, platelet count is low because there is genetic disorder. ⚫ MPL - viral oncogene type of cell marker. Usually seen on ⚫ If a patient is undergoing chemotherapy, there is induced progenitors (BFU, CFU, LD-CFU) and precursors (MK-I, platelets and artificial thrombocytopenia That is why they MK-II, MK-III) are given an artificial thrombopoietin and IL-11. ⚫ CD34 - HSC, indistinguishable, usually seen on ⚫ QUESTION IN BOARDS: What are the hormones or progenitors. cytokines that can be used as therapeutic agent. ⚫ CD41 - Can’t be seen in BFU-Meg, but we can see it the ANSWER: Interleukin-11 and Thrombopoietin other progenitors and precursors. ⚫ IL-6 and IL-3 are not used because they lack artificial ⚫ CD42 ⚫ PF4 - Platelet Factors 4 OTHER HORMONES AND CYTOKINES ⚫ VMF - Von Willebrand Factor, seen on precursors only ⚫ Stem cell factor (kit ligand or mast cell growth factor), ⚫ Fibrinogen - Can be seen on metamegakaryocyte or in Granulocyte-macrophage colony stimulating factor (GM- the part of MK-III, also found in platelet. CSF), Granulocyte-CSF, acetylcholinesterase-derived megakaryocyte growth stimulating peptide ADDITIONAL NOTES ⚫ Acute Myeloid Leukemia (CML) - a type of leukemia CELL DERIVED STIMULATORS OF wherein the problem is your myeloid progenitor. That is MEGAKARYOPOIESIS why M1 to M7, there is problem in monocytes, neutrophils, granulocytes, and erythrocytes. ⚫ M7 - Acute megakaryocytic anemia. ⚫ CD41, CD36, CD42, CD62 - cell markers of megakaryoblasts, progenitors of megakaryocytes. in acute megakaryocytic anemia. ⚫ Markers are antigen. ⚫ IL-3 – for early differentiation of stem cells V.T. BERNARDINO, K.D. JUDAL, A.J. MANGILIT, E.J. SABERON, M.S. SOLMERON, S.C. TUMAGAY, N.T. VELASCO | BSMT 2  TRANS: PLATELET PRODUCTION, STRUCTURE, AND FUNCTION ⚫ IL-6 and IL-11 – act in the presence of TPO to enhance GRANULAR MEGAKARYOCYTE (MK-III) endomitosis, megakaryocyte maturation, and platelet Size: 30-50 µm release. Cytoplasm: Abundant: Pinkish blue in color, very fine and diffusely granular, Usually has an irregular peripheral INHIBITORS border ⚫ Platelet Factor 4 (PF4) Nucleus: Small in comparison to cell size, Multiple nuclei ⚫ B-thromboglobulin may be visible or the nucleus may show multilobulation, ⚫ Neutrophil activating peptide 2 Chromatin is coarser than in the previous stage; No nucleoli ⚫ IL-8 are visible o Note: They have control in the megakaryopoiesis N/C ratio: 2:1 to 1.1 o NOTE: Can be recognize using LPO because it will be MORPHOLOGICALLY IDENTIFIABLE STAGE identify through its shape. ⚫ MK I – Megakaryoblast o There is a multy lobulation of the nucleus. ⚫ MK II – Promegakaryocyte ⚫ MK III - Megakaryocyte MEGAKARYOBLAST (MK-I) ⚫ Size: 14-18 um ⚫ Cytoplasm: varying shades of blue; Usually darker than the myeloblast; May have small, blunt pseudopods; small to moderate amount. Usually a narrow band around the nucleus. As the cell matures, the amount of cytoplasm increases; usually nongranular ⚫ Nucleus: Round, oval or may be kidney shaped; Fine Figure: Megakaryocyte chromatin pattern; Multiple nucleoli that generally stain blue MATURE MEGAKARYOCYTE/ ⚫ N/C Ratio: 10:1 METAMEGAKAYOCYTE ⚫ Begins development of alpha and dense granules (dense bodies) Size: 40-120 µm ⚫ Demarcation System (DMS) – series of membrane-lined Cytoplasm. Contains coarse clumps of granules channel that invade from the plasma membrane and grow aggregating into little bundles, which bud off from the inward to subdivide the entire cytoplasm. periphery to become platelets Nucleus: Multiple nuclei are present or the nucleus is multilobulated; no nucleoli visible N/C ratio: less than 1:1 o Note: thrombopoiesis is happening and there is a fragmentation of cytoplasm. Figure: Megakaryoblast PROMEGAKARYOCYTE (MK-II) ⚫ Size: 15-40 um ⚫ Cytoplasm: More abundant than previous stage; Less basophilic than in the blast; Granules begin to form in the Golgi region ⚫ Nucleus: Chromatin becomes more coarse; Multiple nucleoli are visible; irregular in shape; may even show slight lobulation ⚫ N/C Ratio: 4:1 to 7:1 depending on the ploidy TERMINAL MEGAKARYOCYTE DIFFERENTIATION STAGE Figure: Promegakaryocyte V.T. BERNARDINO, K.D. JUDAL, A.J. MANGILIT, E.J. SABERON, M.S. SOLMERON, S.C. TUMAGAY, N.T. VELASCO | BSMT 3  TRANS: PLATELET PRODUCTION, STRUCTURE, AND FUNCTION TROMBOPOIESIS Thrombopoieisis leaves behind naked megakaryocyte nuclei to be consumed by marrow macrophages. PLATELETS (THROMBOCYTES) Size: 1 to 4 µm Cytoplasm: Light blue to purple; Very granular; consist of two parts: o Chromomere – granular; located centrally o Hyalomere – surrounds the chromomere and is nongranular and clear to light blue Nucleus: None Present NOTE: Platelets is small under the microscope because platelets is just a fragment of megakaryocyte. Cytoplasm is granular but nucleus is not present DEMARCATION SYSTEM AND THROMBOCYTOPOIESIS Demarcation system→ series of membrane-lined channels Figure 1: Platelet (Thrombocyte) that invade from the plasma membrane and grow over the Anucleate blood cells course of differentiation to subdivide the entire cytoplasm. 2.5 µm, MPV (8-10 fL) Platelet shedding N.V. 150 – 400 x 109/L (1) DMS dilates o Slightly lower at both sexes over 65 years old (2) Longitudinal bundles of tubules form o Higher in women (3) Proplatelet processes (cytoplasmic extensions) form → 30% (1/3) of platelets are in the spleen pierce through or between sinusoid lining endothelial cells, 2/3 in the circulation extend to the venous blood and release platelets # PLT/OIF in PBS: 7-21 Trigger primary hemostasis NOTE: Platelet will trigger primary hemostasis per instance, vessel injury. Platelet adheres to the wound, adheres to the collagen. If there’s a wound, in the endothelial, the collagen is exposed and the platelet will adhere to the collagen. All of the platelets that is passing by to the circulation of the blood will stop first to the wounded area then will form a platelet plug (which is the end product of primary hemostasis) to temporarily stop bleeding. Primary hemostasis is short lived, it will then cover by the long lived secondary hemostasis. Figure: Demarcation system and Thrombocytopoiesis Figure 2: Platelets V.T. BERNARDINO, K.D. JUDAL, A.J. MANGILIT, E.J. SABERON, M.S. SOLMERON, S.C. TUMAGAY, N.T. VELASCO | BSMT 4  TRANS: PLATELET PRODUCTION, STRUCTURE, AND FUNCTION STRESS PLATELETS (RETICULATED PLATELETS) STRUCTURE DESCRIPTION Stress platelets is the cause of early release of reticulocytes Peripheral Zone Glycocalyx (outer 6 µm, MPV (12-14 fL) surface membrane of Appear in compensation for thrombocytopenia platelets) EDTA – round Plasma Membrane Citrated – cylindrical and beaded (resembles fragments of (contains carbohydrates and phospholipids) megakaryocytes proplatelet process) NOTE: Stress reticulocytes is normal if there is bleeding, this NOTE: the arrangement of happens when reticulocytes is not yet ready to come out in bone carbohydrates and marrow but it is stressed since our body needs RBC. Therefore, phospholipids are asymmetrical bone marrow will release RBC. Due to stress platelets it will have early, rapid, pro platelet formation. It is not yet the time Sub-membranous area for megakaryocyte to undergo platelet shedding but right away Sol-Gel Zone (cytoskeleton Microfilaments megakaryocyte sheds which results to early and pro release of that maintains the shape of Microtubules platelet. Reticulated platelets are bigger compared to the platelets) normal platelets. Organelle Zone Alpha granules Dense granules Mitochondria (for the production of ATP which serves as an energy) Lysosomal granules NOTE: if the platelet is activated these are the granules that will come out Membranous System Dense tubular system Figure: Stress Platelets Surface connecting system (open DISTRIBUTION AND KINETICS canalicular system) – Production: shed from the megakaryocyte cytoplasm into serves as inner and outer the venous sinuses canal of environment of Cytokines and Hormones: the platelet o TPO o IL-3 – induce early differentiation of stem cells PERIPHERAL ZONE o IL-6 and IL-11 – enhance endomitosis, megakaryocyte PLASMA MEMBRANE maturation Distribution: 2/3 in the blood (Ave. value: 275x109/L; range Bilayer composed of proteins and lipids (phospholipids and of 150-400 x 109/L), 1/3 in the spleen cholesterol) Maturation time in BM: 5 days o Arrangement of Carbohydrates & Lipids- asymmetrical Circulating Life Span: 8-12 days Site of receptors for clotting factors and aggregating agents Destruction: removed by macrophages in the spleen and o Phospholipid bilayer: liver or through consumption in daily coagulation ▪ Phosphatidylchloline and Sphingomyelin mechanisms (Neutral)- predominates the outer plasma Platelet turnover rate = 35,000 ± 4,300 platelets/day (1% membrane RBC everyday) ▪ Phosphatidylinositol, Rebound thrombocytosis Phosphatidylethanolamine, o Following platelet depletion due to increase Phosphatidylserine (Polar)- predominates the megakaryoblast endomitosis inner cytoplasmic layer Rebound thrombocytopenia ▪ Phosphatidylinositol- supplies arachnoid acid in o Following platelet transfusion due to increase the plasma membrane (unsaturated fatty acid that megakaryocyte endocytosis becomes converted to the eicosanoids prostaglandin and thromboxane A2 during platelet activation). ▪ Phosphatidylethanolamine- flips to the outside surface (in cases of release of coagulaion enzyme) in which coagulation enzymes assemble. Figure: Thrombopoiesis NOTE: once the platelets is inactivated it will release the granules and the platelet will now change its shape, if there is changes of the shape PLATELET ULTRASTRUCTURE it means the inner portion of the phospholipid Composed of 60% protein, 30% lipid (mostly (phosphatidylethanolamine) will flip and therefore, phospholipids), 8% carbohydrates, various minerals the phosphatylethanolamine will now have a (electrolytes like calcium, magnesium), water and receptors for the coagulation enzymes. This will be nucleotides needed in the activation of the secondary hemostatis. V.T. BERNARDINO, K.D. JUDAL, A.J. MANGILIT, E.J. SABERON, M.S. SOLMERON, S.C. TUMAGAY, N.T. VELASCO | BSMT 5  TRANS: PLATELET PRODUCTION, STRUCTURE, AND FUNCTION DENSE TUBULAR SYSTEM Condensed remnants of rough ER o NOTE: Remnant of rough endoplasmic reticulum in the megakaryocyte. Sequesters (holds) calcium (important in coagulation system). Bears enzymes that supports platelet activation (Phospholipase A2, Cyclooxygenase, Thromboxane GLYCOCALYX synthetase). Thickness: 20-30 nm The control center for platelet activation is the Dense Outer surface/membrane of the platelet Tubular System. Important for platelet reactions for thrombin and fibrinogen Platlet membrane surface SOL-GEL ZONE Absorbs albumin, fibronogrn and ther plasma proteins- Microtubules, Actin Microfilaments, and Intermediate transports them to storage organelles (endocytosis). Microfilaments control platelet shape change, extension of Maintains a negative surface charge that repels other pseudopods, and secretion of granule contents. platelets. o NOTE: Sol-gel Zone is the platelet’s cytoskeleton. It NOTE: it supplies the negatively charge of the platelets it is in contains proteins and the following parts: Glococalyx. Incorporate with gp Ia, Ib, Ic, IIb, III, IV and V MICROTUBULE Responsible for platelet adhesion and aggregation. Structural support Provides surface adhesion of coagulation factors: I, V, X, Composed of CHON (protein) tubulin which maintains the XI, XII & XIII discoid shape of platelets (disassembles at refrigerator temperature) o NOTE: Whole blood is stored in the refrigerator. Platelets are not refrigerated but are stored in a Room Temperature (Agitator). o If a platelet concentrate is refrigerated, the tubulin/cytoskeleton will be disassembled. To reverse back to the original form after being refrigerated, we warm the platelet with 37°C. o Granules are seen in the Microtubules (Alpha and Dense granules). Contract on activation to encourage expression of alpha SUB-MEMBRANOUS AREA granule contents Beneath plasma membrane Seperates the internal sides of the platelet wall. MICROFILAMENTS Consists of an organized system of microfilaments Composed of actin and myosin which upon stimulation are Site where messages from the external membrane are converted into actomyosin, a contractile CHON important in translated into chemical signals carrying platelet activation clotting retraction. and a charge in the physical structure. o NOTE: Actin serves as the muscle of platelet. During Messages from the external membrane are translated into platelet activation there is an irregularity in the shape chemical signals causing activation and a physical change of the platelet due to the actin and myosin. in the platelet. Mediates platelet contraction important in centralization of granules and eventual release of granular contents, and SURFACE-CONNECTED CANALICULAR SYSTEM/ pseudopod formation. OPEN CANALICULAR SYSTEM (SCCS) Plasma membrane that invades the platelet interior INTERMEDIATE FILAMENTS Serves as a canal of the inner and the outer environment of Desmin and vimentin the platelet. Connect with actin and tubules – maintaining shape of Allows to store additional quantities of the hemostatic platelet. proteins of the glycocalyx The route for endocytosis and secretion of granular ACTIN contents upon activation Anchors plasma membrane glycoproteins and Only -granules exits in SCCS proteoglycans V.T. BERNARDINO, K.D. JUDAL, A.J. MANGILIT, E.J. SABERON, M.S. SOLMERON, S.C. TUMAGAY, N.T. VELASCO | BSMT 6  TRANS: PLATELET PRODUCTION, STRUCTURE, AND FUNCTION o NOTE: causes platelet to contract. It moves near the o NOTE: debris that are not important or platelets are antigens (proteoglycan and glycoprotein). digested by the lysosomal process. NOTE: in the resting platelet (circulating platelet), actin is globular and amorphous. As the cytoplasmic Ca2+ PLATELET FUNCTION concentration increases (injury, inflammation, etc.), actin Play a critical role in hemostasis by forming the primary plug becomes filamentous and contractile. that initially seals vascular defects and by providing a surface that bonds and concentrates activated coagulation DESMIN AND VIMENTIN factors. Connects with actin and tubules to maintain platelet shape. IMPORTANT ROLES OF PLATELETS IN ORGANELLE ZONE HEMOSTASIS ALPHA GRANULES 1. Adhere to injured cells 50 to 80 alpha granules per platelet o If there is a vessel injury, the first responder are o NOTE: passes along the open canalicular system. platelets. Content participates in adhesion, aggregation, and plasma 2. Aggregate at the injury site coagulation. o Temporarily, there is a formation of “platelet plug” to stop the bleeding. Stain GRAY in osmium-dye transmission electron 3. Promote coagulation on their phospholipid surface microscopy preparation. o Once the platelet plug is formed, it Proteins present in granule only: activates/aggregates and trigger the secondary o Beta-thromboglobulin, HMWK, PAI-1, Plasminogen, hemostasis. PF-4, Protein C Inhibitor o Secondary hemostasis → activation of clotting factor Proteins present in granule and plasma: ▪ NOTE: product of primary hemostasis → platelet o Fibronectin, Fibrinogen, Albumin, Immunoglobulins, plug, Factor V, Thrombospondin, VWF ▪ product of secondary hemostasis → fibrin clot o During activation, alpha granules fuse with SCCS and 4. Release biochemical important to hemostasis their contents flow on nearby microenvironment. 5. Induce clot retraction o Gray Platelet Syndrome o Platelet plug will go back to normal because of ▪ Inherited absences of alpha-granule contents secondary hemostasis ▪ Platelets appear large and light gray (Wright’s stain) PLATELET PLUG FORMATION ▪ Diminished platelet aggregation in response to ADP, collagen, epinephrine, and thrombin. End product of primary hemostasis: PLATELET PLUG FORMATION Polar phospholipid exposure + platelet microparticle DENSE BODIES dispersion + release of granule content → ACTIVATION 2 – 7 dense granules / platelet OF SECONDARY HEMOSTASIS o NOTE: alpha granules are more common than dense bodies Stain BLACK in osmium – dye transmission electron microscopy preparation. Contents: ADP, ATP, Serotonin, Calcium, Magnesium o NOTE: Serotonin is important in platelet adhesion Drug activation, dense bodies migrate to plasma membrane and release their contents directly. Table. Contents of Dense Bodies SMALL MOLECULE COMMENT ADP Nonmetabolic, supports neighboring platelet aggregation by binding to ADP receptors P2Y1, P2Y12 ATP Function unknown, but ATP release is detectable upon platelet activation Serotonin Vasoconstrictor that binds endothelial cells and platelet membranes Ca2 and Mg2+ Divalent cations support platelet activation and coagulation ADP, Adenosine diphosphate; ATP, adenosine triphosphate; P2Y1 and P2Y12, members of the purigenic receptor family (receptors that bind purines) LYSOSOMES Stains positive with arysulfatase, beta-glucororonidase, acid phosphatase and catalase. Digest vessel wall matrix components during in vivo aggregation. Digest autophagic debris. V.T. BERNARDINO, K.D. JUDAL, A.J. MANGILIT, E.J. SABERON, M.S. SOLMERON, S.C. TUMAGAY, N.T. VELASCO | BSMT 7  TRANS: PLATELET PRODUCTION, STRUCTURE, AND FUNCTION Figure. Formation of Platelet Plug Summary of Plug Formation: o If there is a vessel injury, collagen will be exposed and can attract the platelets. Platelets will go to the exposed collagen in the epithelial cell → PLATELET ADHESION (platelet adheres to vessel wall caused by the exposure of collagen) o After platelet adhesion, there will be changes on the shape of platelets because it activates the platelets → PLATELET ACTIVATION o Once the platelets activate, it releases the granules which will attract other platelets → PLATELET SECRETION. o Due to the attraction of other platelets, there will be a aggregation → PLATELET AGGREGATION o In order platelet plug formation: ▪ Platelet adhesion ▪ Platelet activation ▪ Platelet secretion ▪ Platelet aggregation o Upon platelet aggregation, there will be platelet plug formation. o Platelet plug will activate secondary hemostasis. REFERENCES Notes from the discussion by Prof. Milwida Josefa B. Villanueva, RMT, MSMT V.T. BERNARDINO, K.D. JUDAL, A.J. MANGILIT, E.J. SABERON, M.S. SOLMERON, S.C. TUMAGAY, N.T. VELASCO | BSMT 8  TRANS: PLATELET PRODUCTION, STRUCTURE, AND FUNCTION V.T. BERNARDINO, K.D. JUDAL, A.J. MANGILIT, E.J. SABERON, M.S. SOLMERON, S.C. TUMAGAY, N.T. VELASCO | BSMT 9