Study
Aids
Glossary of Terms
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4-5. VARIATIONS IN ERYTHROCYTES a. Size. - (1) Anisocytosis. Anisocytosis is a variation in the size of erythrocytes beyond the normal limits. Cells of varying size are seen in the same fields.
- (2) Macrocytes. Macrocytes are erythrocytes larger than nine microns in diameter. These cells may be found in liver disease.
- (3) Microcytes. These erythrocytes are smaller than 6 microns in diameter. These cells are found in thalassemia and other anemias.
b. Shape. - (1) Poikilocytosis. This term describes a marked variation in the shape of erythrocytes. Poikilocytes can be pear-shaped, comma-shaped, oval- shaped, or various other bizarre forms. These cells are encountered in pernicious anemia and many other types of anemia.
Figure 4-2a. Variations in erythrocytes: Poikilocytosis: Sickle cells.
- (2) Sickle cell (Drepanocytes). Sickle cells are abnormal erythrocytes that assume a crescent or sickle-shaped appearance under conditions of reduced oxygen tension. The presence of sickle cells is an inherited abnormality due to the presence of hemoglobin S. Sickle cell anemia is encountered primarily in Blacks.
Figure 4-2b. Variations in erythrocytes:
a. Metarubricytes Anisocytosis
Polychromasia Spherocytosis
- (3) Spherocytes. These are abnormal erythrocytes that are spherical in shape, having a diameter smaller than normal, and a darker stain (without central pallor) than normal erythrocytes. These cells are found in instances of hemolytic anemias and are particularly characteristic of congenital hemolytic jaundice, a hereditary disorder.
Figure 4-2c. Variations in erythrocytes:
Marked Poikilocytosis.
Anisocytosis and Target Cells.
- (4) Ovalocvtes. These cells are abnormal erythrocytes that have an oval or “sausage” shape. They can be found in hereditary elliptocytosis.
Figure 4-2d. Variations in erythrocytes:
Elliptocytes (Oval Erythrocytes).
- (5) Target cells (leptocytes). Target cells are erythrocytes that have deeply stained (pink) centers and borders, separated by a pale ring, giving them a target-like appearance. They are associated with liver disease and certain hemoglobinopathies.
- (6) Burr cells. Burr cells are triangular or crescent-shaped erythrocytes with one or more spiny projections on the periphery. These cells are seen in uremia, acute blood loss, cancer of the stomach and pyruvate kinase deficiency.
Figure 4-2e. Variations in erythrocytes:
Crenated RBC Burr Cells
Acanthocytes 2 Leukocytes - (7) Acanthocytes. Acanthocytes are irregularity-shaped erythrocytes with long spiny projections. They are seen in a congenital abnormality characterized by serum concentration of low density (beta) lipoproteins.
Figure 4-2f. Variations in erythrocytes:
a. Metarubricyte
b. Target Cell
c. Crenated RBC.
- (8) Crenated erythrocytes. This condition occurs when blood films dry too slowly and the surrounding plasma becomes hypertonic. There is no pathological significance when they are found in blood smears.
- (9) Schistocytes. These are red blood cell fragments. Frequently these cells have a hemispherical shape (helmet cells).
- (10) Rouleaux formation. This phenomenon is adherence of erythrocytes to one another presenting a stack-of-coins appearance. It occurs in conditions characterized by increased amounts of fibrinogen and globulin.
c. Staining. - (1) Hypochramia. Hypochramia is a condition in which the normal central pallor is increased due to decreased hemoglobin content. This condition is characteristic of many anemias.
Figure 4-2g. Variations in erythrocytes:
Hypochromic macrocytic erythrocytes.
- (2) Polychromatophilia. This term describes non-nucleated erythrocytes that show bluish coloration instead of light pink. Polychromatophilia is due to the fact that the cytoplasm of these cells does not mature, resulting in the abnormal persistence of the basophilic cytoplasm of the earlier nucleated stages.
d. Inclusions. - (1) HoweII-Jolly bodies. These are nuclear remnants found in the erythrocytes of the blood in various anemias. They are round, dark violet granules about one micron in diameter. Generally, only one Howell-Jolly body will be found in any one red cell. However, two or more may sometimes be present. HoweII-Jolly bodies generally indicate absent or non-functioning spleen. They occur in megalobastic anemia and in other forms of nuclear maturation defects.
Figure 4-2h. Variations in erythrocytes:
a. Metarubricyte
b. Howell-Jolly Bodies
- (2) Cabot's rings (ring bodies). These are bluish threadlike rings found in the red cells in the blood of patients with severe anemias. They are interpreted as remnants of the nuclear membrane and appear as ring or “figure-eight' structures. Usually only one such structure will be found in any one red cell.
Figure 4-2i. Variations in erythrocytes:
a. Cabot Ring. - (3) Basophilic stippling. Round, small, blue-purple granules of varying size in the cytoplasm of the red cell represent a condensation of the immature basophilic substance (see poly-chromatophilia) that normally disappears with maturity. This is known as basophilic stippling. It can be demonstrated by standard staining techniques in contrast to reticulocyte filaments that require a special stain. Stippling occurs in anemias and heavy metal poisoning (lead, zinc, silver, mercury, bismuth) and denotes immaturity of the cell.
Figure 4-2j. Variations in erythrocytes:
a. Basophilic Stippled Erythrocyte. - (4) Heinz-Ehrlich bodies. These are small inclusions found primarily in those hemolytic anemias induced by toxins. They are round, refractile bodies inside the erythrocyte and are visible only in unfixed smears. It is thought that they are proteins that have been dematured and that they are an indication of erythrocyte injury.
- (5) Siderocytes. These are erythrocytes containing iron deposits. These deposits indicate an incomplete reduction of the iron from ferric to the ferrous state that is normally found in hemoglobin. Prussian blue stain must be used to readily demonstrate these cells.
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Figure 4-2k. Variations in erythrocytes:
a. Rubricytes (Pernicious Anemia).
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Figure 4-2l. Variations in erythrocytes:
a. Metarubricyte (Pernicious Anemia) | e. Megaloblastic Erythrocytes. The development of megaloblastic cells is caused by a deficiency of vitamin B12 or folic acid. Pernicious anemia is a disease considered to be due to a deficiency in vitamin B12 and/or certain related growth factors. With this deficiency, the erythrocytes do not mature normally and are generally larger than normal. The most notable characteristic of this abnormal maturation is a difference in the rates of maturation of the cytoplasm and the nucleus. The development of the nucleus is slower than that of the cytoplasm, so that in the more mature of the nucleated forms a spongy nucleus as well as an exceptionally large size may be observed. Nuclear chromatin in the megaloblast is much finer and is without the clumps observed in the rubriblast. Such development is termed asynchronism. The mature cell is large (about 10 microns) and is termed a megalocyte. The younger cells of this series are named by adding the suffix “pernicious anemia type," that is rubricyte, pernicious anemia type, and so forth.
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