AUTORADIOGRAPHIC AND HISTOCHEMICAL STUDIES ON DIFFERENTIATION OF MYELOIDS AND MONOCYTES IN HUMAN CORD BLOOD IN VITRO

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Human umbilical cord blood cells were cultured in suspension for 15 days. Characteristics of the cord blood cells grown in culture were studied in relation to histochemical features with ³H-thymidine (³H-TdR) labeling in the course of the 15-day culture. The labeling index after 1 day was 2.9% of mononuclear cells, naphthol AS-D chloroacetate esterase (NACE) and peroxidase positive cells comprised about 83% of all the labeled cells. In the study with blood from 38 to 41 weeks gestation, the percentage of ³H-TdR labeled cells and histochemically stained cells were found more or less identical regardless of the gestational age. No labeled cells with nonspecific esterase activity were observed in 1 and 5-day cultures. The total cell population decreased in 5 days whereas the labeled cells increased to 19%. The labeled cells showing NACE and peroxidase activities decreased markedly after 5 days. After 10-15 days of culture, both cell number and the labeling index decreased, whereas the labeled cells with peroxidase and luxol fast blue (LFB) activity increased. At the same time, the appearance of the labeled cells having nonspecific esterase activity was observed.