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Another example of a malignant cell. This cell has a smooth chromatin pattern similar to the chromatin pattern commonly seen in blast cells. This cell has a high nuclear to cytoplasm (NC) ratio which is typical for malignant cells. No nucleoli are visible in this cell although malignant cells often have large nucleoli.

Under normal conditions, Howell-Jolly bodies are thought to be remnants of nuclear fragments due to incomplete expulsion of the nucleus. In pathological conditions, they are aggregates of chromosomes which have separated from the mitotic spindle during abnormal mitosis. Single or multiple Howell-Jolly bodies may be found in a red cell. A single HJ body in a red cell may be seen in megaloblastic anemia, hemolytic anemia such as sickle cell anemia and after splenectomy. Megaloblastic anemia or abnormal erythropoiesis is usually present when multiple Howell-Jolly bodies are observed in a single cell.

Since Howell-Jolly bodies are nuclear remnants, they can also be seen in the cytoplasm of the young nucleated red cells.

Thin, red-violet-staining strands in the shape of rings, figure eights, or shapes of the letter B may on rare occasions be seen in erythrocytes. These structures are called Cabot rings. Although the origin of Cabot rings continues to be illusive, they are not nuclear fragments since they test Feulgen negative. The rings are probably microtubules remaining from a mitotic spindle. Cabot rings have been observed in a few cases of megaloblastic anemia, lead poisoning and other disorders of erythropoiesis, as well as, after a splenectomy.

A “dirty bomb” is a crude method for spreading radiation over a substantial area. It does not create a nuclear blast. It is made by packing dynamite or some other conventional explosive with virtually any type of radioactive material. When the explosive is detonated, it spews the radioactive material over the surrounding area.

The next stage is the fully developed megakaryocyte. It typically shows nuclear divisions and abundant very granular cytoplasm. Megakaryocytes are the largest cell found in normal bone marrow and can range in size from 30-100 microns. The nuclear chromatin pattern is coarse. Nucleoli are absent.

It is also important to examine the morphology of platelets. One megakaryocyte shows a single nucleus surrounded by cytoplasm which will eventually break off to form platelets. The other one at the arrow shows a lobated nucleus which has divided several times; the large amount of cytoplasm surrounding this nucleus means that this cell will be able to produce more platelets. In general, as the megakaryocyte gets older, it forms more nuclear lobes, more cytoplasm and therefore is able to produce more platelets.

Lymphocytes "transform" in response to antigenic stimuli.Their nuclei becomes larger with more open chromatin and a greater degree of nuclear folding.The cytoplasm becomes abundant, the number of azurophilic granules may be increased and vacuoles may be present.The cytoplasmic membrane may be easily indented by surrounding red blood cells, resulting in a scalloped appearance of the cell's outer edge.These lymphocytes may also be referred to as reactive, activated or stimulated.

The nucleus of a band neutrophil is sausage or band-shaped (U-shaped).Sometimes it appears folded or twisted, thus making identification more difficult.The nucleus stains a deep purplish-blue color, and the nuclear chromatin appears condensed, coarse, and clumped.

The nucleus is a deep reddish-purple color, and the chromatin has a coarse, clumped texture.The seg nucleus normally has from 2-5 lobes, with an average of 3.The lobes are connected to each other by a fine filament or strand of nuclear membrane.A filament has been defined as a thread-like strip which is so narrow that there is no visible nuclear material between the two sides.

A drop of dilute acetic acid enhances the nuclear detail of the white blood cells making them much easier to distinguish from the epithelial cells.

A Barr body appears as a small drumstick-like projection on one of the lobes of a some of the neutrophil in females. Barr bodies are attached to the nuclear lobe by a single narrow stalk which distinguishes them from other thicker projections, sometimes referred to as "clubs." Clubs have a thicker, and sometimes, a double stalk. This projection can be seen in both males and females and has no clinical significance. Barr bodies must also be distinguished from hair-like projections sometimes seen in the band form, following irradiation or in patients with a malignant tumor that has metastasized. Since Barr bodies are the morphological expression of the inactivated X chromosome, one Barr body can be seen in up to 3% of the neutrophils on a female's peripheral blood slide. In rare chromosome disorders in which three or more X chromosomes are present, two to three Barr bodies per neutrophil can be seen. Recognition of a Barr body in a neutrophil is important in order to avoid reporting it as abnormal unless two or more per neutrophil are seen.

The large cell illustrated in this photograph of a Wright/Giemsa-stained bone marrow smear is a megakaryocyte. This megakaryocyte appears mature. The nucleus has at least 8 lobes and the nuclear chromatin is coarse and distinct. Clusters of young platelets are being released from distinct platelet territories at the periphery of the cytoplasm (blue arrows). When mature, each megakaryocyte produces approximately 4000 platelets/day. Production can expand by 8-fold during times of increased demand and under the stimulus of thrombopoietin.

The Pelger-Huet anomaly is a congenitally acquired condition of nuclear segmentation and is clinically insignificant. There is no loss of cellular function.The condition can be suspected if typical bilobed, "pince-nez" nuclei are observed (left upper frame in the composite photograph).Band neutrophils usually have two distinct lobes, connected by a relatively short but thick bridge as illustrated in the upper and lower right frames. Monolobated cells may also be encountered, as illustrated in the lower left frame. If these are seen in significant numbers, the possibility of a homozygous Pelger-Huet should be considered.

In this photograph of blood cells from yet another submitted slide, we find cells resembling lymphoblasts with increased nuclear/cytoplasmic ratios and dense, finely meshed nuclear chromatin. In addition, note the extrusion of delicate strands of cytoplasm from the outer cell membranes (blue arrow). These are cells connoting hairy cell leukemia (HCL). Under scanning electron microscopy, the cytoplasmic extensions appear to be either slender microvilli or delicate pseudopods. The most helpful confirmatory finding is the detection of acid phosphatase isoenzymne 5 in the cytoplasm of suspected hairy cells by staining. The enzyme concentrates primarily in golgi bodies and in the nuclear membrane and its staining is not inhibited by the addition of tartrate. Stated in another way, hairy cells on the peripheral smears are detected by their staining positively for tartrate-resistant acid phosphatase. Be suspicious of HCL if marrow resists aspiration-a consequence of reticulin fibrosis of the marrow in HCL.