Normal red blood cell findings with slight variance

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Normal red blood cell findings with slight variance in size of the erythrocytes. A lymphocyte (1) and a few thrombocytes (2) are seen. The erythrocytes are slightly smaller than the nucleus of the lymphocyte nucleus. Theml, Color Atlas of Hematology © 2004 Thieme All rights reserved. Usage subject to terms and conditions of license.
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34 Immature White Cell Precursors: Myeloblasts and Promyelocytes Myeloblasts are the least mature cells in the granulocyte lineage. Mononu- clear, round-to-ovoid cells, they may be distinguished from proerythro- blasts by the finer, “grainy” reticular structure of their nuclei and the faintly basophilic cytoplasm. On first impression, they may look like large or even small lymphocytes (micromyeloblasts), but the delicate structure of their nuclei always gives them away as myeloblasts. In some areas, con- densed chromatin may start to look like nucleoli. Sporadically, the cyto- plasm contains azurophilic granules. Promyelocytes are the product of myeloblast division, and usually grow larger than their progenitor cells. During maturation, their nuclei show an increasingly coarse chromatin structure. The nucleus is eccentric; the lighter zone over its bay-like indentation corresponds to the Golgi appara- tus. The wide layer of basophilic cytoplasm contains copious large azurophilic granules containing peroxidases, hydrolases, and other enzymes. These granulations also exist scattered all around the nucleus, as may be seen by focusing on different planes of the preparation using the micrometer adjustment on the microscope. Diagnostic Implications. Ordinarily, both cell types are encountered only in the bone marrow, where they are the most actively dividing cells and main progenitors of granulocytes. In times of increased granulocyte pro- duction, promyelocytes and (in rare cases) myeloblasts may be released into the blood stream (pathological left shift, see p. 112). Under strong re- generation pressure from the erythrocyte series, too—e.g., during the compensation phase following various anemias—immature white cell precursors, like the red cell precursors, may be swept into the peripheral blood. Bone marrow involvement by tumor metastases also increases the permeability of the blood–bone marrow barrier for immature white cell precursors (for an overview, see p. 112ff.). In some acute forms of leukemia, myeloblasts (and also, rarely, pro- myelocytes) dominate the blood analysis (p. 97). Normal Cells of the Blood and Hematopoietic Organs Theml, Color Atlas of Hematology © 2004 Thieme All rights reserved. Usage subject to terms and conditions of license.
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35 a b c d Round cells with “grainy” reticular chromatin structure are blasts, not lymphocytes Fig. 10 Granulocyte precursors. a The least mature precursor in granulopoiesis is the myeloblast, which is released into the blood stream only under pathological conditions. A large myeloblast is shown with a fine reticular nuclear structure and a narrow layer of slightly basophilic cytoplasm without granules. b Myeloblast and
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  • Hematology, Test, Bone marrow, white blood cell, Color Atlas of Hematology

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