The introductory chapter of the Atlas relating to laboratory hematology presents the methods of determination of hematopogical parameters with specific view to the working principle of different hematologic counters. All counters give good results if the blood picture is normal; if the blood picture is pathological, there are specific limitations when thrombocytes are low or very high (> 1 million/µl), when leukocytes are high (>100000/µl), and in case of immature cells.
If thrombocyte aggregates are present, there is danger of making a wrong lab report with low values of thrombocytes. Cell counters cannot register large aggregates of platelets and giant platelets (>20 fl). In these cases it is necessary to check the result under the microscope.

 The chapter Laboratory Blood Analysis describes the determination of red blood cell, reticulocytes, leukocytes and thrombocytes (number and analysis of elementary morphologic data with the description of microscopic control of blood smear and the working system of the counters).
Blood analysis is determination of the appearance, size and other characteristics of cells on the peripheral blood smear. These analyses can be followed by the examination of the bone marrow (puncture and biopsy), lymph nodes (puncture and biopsy), ands spleen (puncture). In the peripheral blood of healthy people there are only mature cells of different blood lineages:

 erythrocytes and rare reticulocytes;
 mature granulocytes (segmented granulocytes and some non-segmented neutrophilic granulocytes, basophilic granulocytes, and eosinophilic granulocytes),
 mature lymphocytes, and mature monocytes;
 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.