Posner, Carl; Poikilocytosis

POSNER, Carl (1854–1928). Upon graduating from the medical faculty in Giessen in 1880, Posner worked for several years as an assistant at the Pathological Institute under Seitz, and then moved to Berlin, where he specialized in urology. Despite the fact that he did not head any inpatient facility, Posner was a major figure not only in Berlin but throughout Europe. Posner gained wide renown for his work on the microscopy of secretions of the urogenital organs. Posner was chairman of the Berlin Urological Society, chairman of German congresses, and vice-chairman of the International Society of Urology. For a long time, Posner served as editorial secretary of the Berliner klinische Wochenschrift, edited Virchows Jahresberichte together with Waldeyer, and was a member of the editorial board of the Zeitschrift für Urologie from its very inception. The main body of Posner's work, scattered across a number of periodicals, concerns the microscopy of urine, secretions of the sex glands, and the morphology of semen and prostatic fluid. Two of Posner's monographs, which went through several editions in Germany, were translated into Russian (Diagnostics of Urogenital Diseases, Moscow, 1895; Diagnostic and Prognostic Significance of Urinary Sediments, Moscow, 1928). POIKILOCYTOSIS, a change in the shape of red blood cells: instead of the usual round corpuscles, erythrocytes of an irregular pear-like or club-like shape are encountered, with one or many processes, notches, etc. Poikilocytosis is observed, apparently, only in dry blood smears; in histological preparations, poikilocytosis is absent; this fact indicates that poikilocytosis is not a pre-existing phenomenon, but one that arises in connection with the instability of erythrocytes, which is revealed upon contact with the external environment. Poikilocytosis has no special diagnostic significance and is observed in anemias of the most diverse character, and in the majority of cases, the degree of poikilocytosis runs parallel to the severity of the anemia. Significant poikilocytosis is encountered in chlorosis, as well as in lead poisoning. Poikilocytosis is noted, for the most part, simultaneously with anisocytosis. Since the time of Ehrlich, it has been assumed that poikilocytosis is caused by a change in the isotonicity of the serum. However, in the origin of poikilocytosis, apparently, besides the indicated factor, the formation in the bone marrow of unstable elements with disturbed structure and insufficient resistance also plays a role.