Immature cells - blasts - have larger diameter than mature cells, their nucleocytoplasmatic ratio is larger, structure of chromatin finer, the nucleus contains nucleoli, the cytoplasm is basophilic and does not contain granules.
During the maturation, the cells become smaller, nucleocytoplasmatic ratio decreases, the chromatin condenses and its coloration is more intensified. The nucleolus disappears, the cytoplasm loses its basophilic character, and, according to its appearance and contents, the cell gets the characteristics of a mature cell of the corresponding cell lineage. In normal blood cells, the maturation of the cell and cytoplasm proceeds synchronously.
Asynchronism during the maturation of the cell and cytoplasm is a sign of abnormality. By staining the blood smears and punctates with May-Grünwald-Giemsa method, numerous data about cells can be obtained. However, it is often necessary to use some other staining methods. They can establish the presence of some substances in the cell using cytochemical and cytoenzymatic reactions. The following substances are often determined in the cell:
- Myeloperoxidase (benzidine and hydrogen peroxide);
- Leukocyte alkaline phosphatase (naphtol is released from phosphate ester and coupled with diazonium salt, resulting in a colored insoluble compound);
- Nonspecific esterase in monocytes (releasing of naphtol from its acetate ester and rapidly coupling with diazonim salt);
- Lipids (sudan black B reaction); and
- Glycogen (periodic acid-Schiff (PAS) stain).
In the peripheral blood of healthy people there are only mature cells of different blood lineages:
- erythrocytes and rare reticulocytes belonging to the erythrocytic lineage;
- mature granulocytes (segmented granulocytes and some non-segmented neutrophilic granulocytes, basophilic granulocytes, and eosinophilic granulocytes), mature lymphocytes, and mature monocytes belonging to the leukocytic lineage; and
- mature platelets - thrombocytes.
Each cell type has characteristic appearance and can be easily distinguished.
In some diseases immature cells of some lineages may appear in the peripheral blood. On the other hand, mature cells of some blood cells in various diseases have altered appearance.
In order to establish the diagnosis and improve the therapeutic efficacy, it is necessary to observe changes in mature cells of blood lineages, to recognize some cells of the same bloodline, and to differentiate immature cells of blood lineages.
In order to distinguish the cells, it is necessary to observe the following features:
- size of the cell,
- size of the cytoplasm,
- coloration of the cytoplasm,
- presence of granules in the cytoplasm, their number, arrangement, size, and coloration,
- shape of the nucleus,
- size of the nucleus,
- rate between the size of the nucleus and the cytoplasm (N/C),
- structure of the chromatin in the nucleus, and
- presence of nucleoli in the nucleus.
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