Morphologic Characteristics of Erythroid Precursors

Pronormoblast (rubriblast): 1% of Nucleated Cells in BM. Size = 20-25 μm. High N/C ratio (8:1) 1-3 faint nucleoli  Lacy chromatin  Basophilic normoblast (prorubricyte): 1-3% of nucleated cells in BM. Size = 16-18 μm Moderate N/C ratio (6:1) Indistinct nucleoli coarsening chromatin Polychromatophilic normoblast...

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Thymus

          The thymus is a lymphopoietic organ located in the upper part of the anterior mediastinum. It is a bilobular organ demarcated into an outer cortex and central medulla. The cortex is densely packed with small lymphocytes (thymocytes), cortical epithelial cells, and a few macrophages. The medulla is less...

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Extramedullary Hematopoiesis

           Hematopoiesis in the bone marrow is called medullary hematopoiesis or intramedullary hematopoiesis.    Blood cell production in hematopoietic tissue other than bone marrow is called extramedullary hematopoiesis.    In certain hematologic disorders when hyperplasia...

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Sites of Hematopoiesis

      Hematopoiesis/Hemopoiesis is the process by whitch blood cells are formed.  Sites of Hematopoiesis Yolk sac      From the 18th day after fertilization, the yolk sac begins hematopoiesis. The cells made here are erythrocytes & few macrophages. Aorta-gonads-mesonephros (AGM) region     ...

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Activated Partial Thromboplastin Time (APTT / aPTT / PTT) Test Procedure

Principle      Platelet-poor plasma is added to an equal volume of partial thromboplastin reagent and warmed to 37°C for an exact incubation time. Pre-warmed (37°C) calcium chloride reagent (0.025M) is added to this mixture to activate the coagulation cascade. The time required for clot formation is recorded. Clot...

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Thrombin Time (TT) Test

     TT has an important role as a screening test because it measures the conversion of fibrinogen to fibrin by adding excess thrombin to undiluted plasma. Because the additional clotting factors previously measured in the PT and APTT have no effect on this test, TT is generally useful for evaluating other parameters...

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Qualitative D-Dimer Test

Principle      D-dimer is a fibrin fragment that results when plasmin acts on cross-linked fibrin in the presence of factor XIII. D-dimers are produced from an insoluble fibrin clot. Available since the 1990s, this semiquantitative assay provides evidence of normal or abnormal levels of D-dimer. Latex particles are...

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Prothrombin Time (PT) Manual Test Procedure

Principle      The addition of pre-warmed (37°C) platelet-poor plasma to thromboplastin-calcium reagent activates the coagulation cascade at Factor VII. The time required for clot formation is recorded. Clot formation may be detected by optical or electromechanical methods using manual, semi-automated, or automated...

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Hemacytometer

          Cell counts are performed manually by diluting blood with a diluent, loading a small amount of the diluted sample on a ruled device (hemacytometer), and counting the cells microscopically. The hemacytometer consists of two side-by-side identically ruled glass platforms mounted in a glass holder....

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Anticagulants

Most tests performed in the hematology laboratory involve anticoagulated blood. Once the blood has left the body, a series of reactions occurs causing blood to clot within minutes. To prevent coagulation from occurring, a substance called an anticoagulant is mixed with the blood. Three anticoagulants are used in the hematology laboratory:- Ethylenediaminetetraacetic...

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Sickle Cell Screening Procedure

v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} Principle:-      The sickle screen kit provides a procedure based on hemoglobin solubility. Hemoglobin S is insoluble when combined with a buffer and a reducing agent. This occurs when...

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Functions of the Spleen

Hematopoietic function:- Can produce white blood cells, red blood cells, and platelets if necessary. Reservoir function:- One-third of platelets and granulocytes are stored in the spleen. Filtration functions:- Aging red blood cells are destroyed. Spleen removes inclusion from red blood cells. If red blood cell membrane is less deformable...

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Lineage-specific Cytokine Regulation

LINEAGE-SPECIFIC CYTOKINE REGULATION Erythropoiesis: In the erythroid lineage, progenitor cells give rise to two distinct types of erythroid colonies in culture. A primitive progenitor cell, the BFU-E, is relatively insensitive to EPO and forms large colonies after 14 days in the form of bursts. Production of BFU-E colonies was originally described...

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