Hematology

HEMATOLOGY (from Greek haima-blood and logos-teaching), the science of blood, which includes the study of the formed elements of blood suspended in its plasma (morphological H.), and the study of plasma properties (serological H.). Until recently, H. was understood, mainly, as morphological H. In recent times, however, more attention has been paid to serological H. - H. includes the study of: a) morphological features of the formed elements of blood, their embryonic and postembryonic development, as well as the properties of plasma (see Blood); b) symptomatic changes in blood in various diseases and c) the clinic and pathological anatomy of the so-called "blood diseases" (see Hematopoiesis). The practical significance of H. is determined by the place occupied in clinical practice by the department of blood diseases. The study of the "blood picture" in various diseases, especially infectious ones, has also acquired no less significance as a diagnostic and prognostic method (see Hemogram, Blood). - H. has its roots in deep antiquity. The view of blood as the most important principle of life found expression in the Latin formula: "sanguis vita vitae est". According to this view of blood, in the times of Hippocrates and Aristotle, for treatment purposes, patients were fed blood. In the Middle Ages, the concept of the healing properties of blood strengthened so much that a method was proposed for sucking it from healthy people by patients, and later also the method of direct blood transfusion. With the invention of the microscope, the study of blood morphology began. In 1673, Leeuwenhoek discovered red blood cells, later Hewson discovered white blood cells. These discoveries were preceded (1628) by Harvey's establishment of the laws of blood circulation. The first researcher who attempted to isolate from the mass of various diseases a special group of blood diseases was Schonlein, who called this group of diseases hematoses. In his description, he mainly dwells on the symptoms of hemorrhages, but he also includes inflammations and new formations in the group of hematoses. Among the "hematoses", Schonlein singled out a group with hemorrhagic diathesis; in particular, he described purpura. Through the research of Cohnheim (1867), the predominant role of blood elements in the inflammatory process, and accordingly in infectious diseases, was established. The concept of "blood diseases" originated in clinical practice, and its justification was found in pathological anatomy. In 1845, Virchow described leukemia. At the same time, he established that the leukemic process is localized in the hematopoietic organs and that changes in the blood are of a secondary nature. The study of embryonic hematopoiesis began in 1845 with the research of Kolliker. In 1868, Biermer clinically distinguished among anemias a special disease - progressive pernicious anemia. The characteristic blood picture of this disease - macro- megaloblastic hyperchromic erythrocytes - was established somewhat later, in the 1880s, by Ehrlich. In 1868, Neumann established that the bone marrow is the site of formation of red blood cells. In 1870, Neumann proved the importance of the bone marrow in the development of leukemias. The era of morphological study of blood begins with the basic brilliant works of Ehrlich. His first works in this direction date back to 1878 and 1879. Ehrlich introduced the study of dry blood preparations, which he prepared on cover glasses. Methodically and analytically studying the dyes and stainability of various blood elements, Ehrlich distinguished three types of granulocytes, lymphocytes, and mononuclears, established the concept of polychromasia of erythrocytes and various types of erythroblasts. He built a whole doctrine of the specificity and function of grains and began to apply the obtained facts in clinical practice. In 1868, he described for the first time the so-called aplastic anemia. In 1878-79, Hayem described in detail the third formed element of blood under the name of hemoblasts. In 1882, Bizzozero gave them the name of blood plates. In 1892, Mechnikov singled out a special system of cells characterized by the ability to phagocytosis. Aschoff's modern doctrine of the reticulo-endothelial system is connected with the works of Mechnikov. Having divided leukocytes into granular forms (granulocytes and large mononuclear leukocytes included in them) and non-granular (lymphocytes), Ehrlich considered them derivatives of different systems - myelogenous and lymphatic (dualistic theory of hematopoiesis). The most prominent adherent of this theory at present is Naegeli. In opposition to Ehrlich's dualism, the unitary theory of hematopoiesis was put forward (Maximov, 1907-1909; Weidenreich, 1911), according to which all types of blood cells develop from lymphocytes. An important step in the development of H. was the introduction of the method of vital staining. The method was developed by Ehrlich's student Goldman (Goldmann, 1909), Aschoff and Kiyono in 1913 and by Kiyono in 1914. Using it, Aschoff created the doctrine of the reticulo-endothelial system, which occupies a prominent place in modern H. Some authors - Schridde, Ferrata, Sysoev - assign the reticulo-endothelial system the main role in hematopoiesis, considering its cells the source of origin of all blood elements. - A great achievement of H. is the application of Carrel's tissue culture method in solving hematological questions (Maximov from 1916). The doctrine of Arneth (1904) on qualitative changes in neutrophil elements is of great importance in studying symptomatic changes in blood. Arneth's doctrine, in modified and simplified form by Schilling ("Schilling hemogram"), entered into clinical practice. In the clinic of blood diseases, the study of the bone marrow obtained by trepanation (Seyfarth, 1924) and simple puncture (Arkin, 1928) also acquires significance. For the most recent years, the development of functional H. can be noted, i.e., the doctrine of erythropoiesis and hemolysis as the basic processes determining the composition of blood. In pathological deviations, these processes cause various types of anemia and polycythemia. To determine the state of erythropoiesis, the method of determining the percentage content in the blood of red blood cells of the so-called substantia reticulo-granulo-filamentosa (Pappenheim, Cesaris-Demel), otherwise -"reticulocytes", has been introduced into clinical practice. To determine the degree of hemolysis, the determination of the amount of bilirubin in serum (Hymans van der Bergh) and urobilinogen in urine and especially in feces (Eppinger) is used. - The most prominent representatives of H. in Russia are Usov and Romanovsky, who proposed his classic staining method (eosin and azure-containing blue), which formed the basis of all currently used methods of panoptic staining (Giemsa, Pappenheim, Leishman, etc.). The significance of Mechnikov has been indicated above. It should be further pointed out Ehrlich's collaborator - Kurlov ("Observations on splenectomized guinea pigs", 1889) and Kryukov ("Structure of blood cells", 1911; "Morphology of blood", 1920). One of the most outstanding contemporary hematologists in the world is Maximov, whose works over thirty years (since 1899) are fundamental and mainly concern the study of hematopoiesis.