Proliferation of an unspecific esterase positive (monocytopoietic) cell system in human bone marrow as observed from nucleic acid synthesis

In order to study the proliferation activity of the unspecific esterase positive cells (EPC) of the bone marrow, which are claimed to be monocytic precursor cells, bone marrow aspirate of a normal human being was incubated with H3-thymidine. The smears were stained for demonstration of the Naphthol-AS-acetate esterase and with the Pappenheim stain. In the EPC's the DNA synthesis was investigated by combined application of cytophotometric measurement of the DNA content (Feulgen photometry) and of autoradiography.