Drepanocytes Information and Courses from MediaLab, Inc.
These are the MediaLab courses that cover Drepanocytes and links to relevant pages within the course.
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|The Sickling Process, Continued|
The sickling process progresses through stages of nucleation, growth and alignment. Nucleation involves the aggregation of a small number of hemoglobin tetramers into clusters or short linear polymers. This stage is also called the lag phase. These clusters may be reversed upon re-oxygenation. With each repeated occurrence, the polymers continue to grow. In this polymerization stage, the internal cellular viscosity increases.Eventually the fibers that are formed become irreversible crystalline structures, which align into bundles, thus creating the pointed elongated and typically crescent shaped morphologies associated with sickle cells (drepanocytes) as seen in the peripheral blood field below.
|RBC Morphology in Sickle Cell Trait (HbSA)|
Codocytes, also referred to as target cells can be observed on the peripheral blood smear from a patient with sickle cell trait (HbSA), as indicated by the arrows in the image on the right. Codocytes are cells that can be seen in hemoglobinopathies, thalassemia, iron deficiency, and other anemias where there is a decrease in the mean corpuscular hemoglobin concentration (MCHC).Sickle cell trait will not usually show completely sickled cells because of the HbA that is present in each cell. HbA usually comprises greater than 60% of the hemoglobin in HbSA.However, rare drepanocytes (sickle cells) and occlusive crisis may be found during times of extreme exercise and fluid restriction.
|RBC Morphology in Sickle Cell Disease (HbSS)|
Sickle Cell Anemia (HbSS) is a hemolytic anemia, characterized by the presence of drepanocytes (sickle cells) and polychromasia (increased reticulocytes). Nucleated red blood cells (NRBCs) may be seen during episodes of severe hemolysis. The absence of polychromasia may indicate aplastic crisis. The homozygous state of hemoglobin SS causes RBCs to take on the characteristic sickle shape when hemoglobin is in a deoxygenated state. The name "sickle" comes from the tool (seen in the upper image) that is used to manually cut hay. When RBCs sickle they take on the same shape as the blade of the sickle, as seen in the bottom image.
|Guidelines for Reporting Red Blood Cell Morphology|
Cell TypeRBC Morphology Reporting Per High Power Field (400x)FewModerateManyAcanthocytes (spur cells)Up to 1% of the fieldor1-2 cells per field1-2.5% of the fieldor3-5 cells per field> 2.5% of the fieldor> 5 cells per fieldFragmented red cells (schistocytes, helmet cells, keratocytes/horn cells)Polychromatophilic cellsSickle cells (drepanocytes)SpherocytesTeardrop cells (dacrocytes).FewModerateManyEchinocytes (burr cells) 5-25% of the fieldor10-50 cells per field25 - 50% of the fieldor51-100 cells per field> 50% of the fieldor> 100 cells per fieldHypochromic cells Macrocytes Microcytes Ovalocytes (elliptocytes) Stomatocytes Target cells (codocytes)....Double Cell PopulationReport if presentRBC AgglutinationRouleaux