[Morphological studies on the behavior of bone marrow cells in vitro. VI. Observations on erythroblasts]

[Morphological phase-contrast cinematographic studies on the behavior of bone marrow cells in vitro. X. Myeloblasts and monoblasts]

The myeloblast is nearly of the same size as the lymphozyte and has the same nucleus cytoplasma ratio of 0.7 but differs from it in its morphology, its high frequency of multiplication, and by its kinetic behaviour. By phase contrast observation the transformation of the myeloblast into the promyelocyte has been seen several times. The myeloblast like the lymphocyte is able to move although at a much slower speed. By locomotion the myeloblast, and likewise the lymphocyte can move between blood and bone marrow. Of the granulocytopoietic series only the promyelocyte and the myelocyte with their nuclear cytoplasm relation of 0.3 are found in the bone marrow. The monoblast but is about twice its size, and moves less often. Apart from its transformation into promonocyte, monocyte and histiocyte, the monoblast may evalue in another way: it grows into a cell of doubled size with the same nucleus cytoplasm ratio 0.7 in whose cytoplasm are seen a lot of big granules. The cell may now be characterized as a tissue macrophage or mastcell. In consequence a frequently multiplying basophilic cell with a coarse nuclear structure and nucleoli, grows from a diameter of 6.5 to one of 13.0 mum without marked morphologic change apart from becoming alpha-NA-Esterase positive and acquiring big lysosomes. When this haemocytoblast is small (K 1/4 to K 1/2), it can be triggered into the granulocytopoietic series, when it is bigger (K 1/2 to K1) into the monocytopoietic series, or in the size K1 to K2 by erythropoietin into the erythropoietic series. If no triggering takes place, the cell degenerates after having granulated. The lymphopoietic system is not connected to this system of stem cells committed to the granulocytopoietic, the monocytopoietic and the erythropoietic series. Therefore we postulate a dual haematopoietic system. In acute leukemias the spread of size of cells and nuclei is wider and kinetically active stem cells are rarer. Only leukemic promyelocytes are in locomotion vividly, in contrast to the normal ones. In leukemic myeloblasts there are fewer mitoses than in normal ones, but in leukemic promyelocytes and monoblasts the mitotic frequency is not reduced.

[Quantitative determination of human bone marrow proliferation kinetics during three culture days]

In order to obtaon of human bone marrow cells, fresh bioptic material was homogenized and the cell suspensions were incubated for 72 hs in a fluid medium. After 24, 48 and 72 hs of incubation the total cell number of the culture was determined. At the same time differential counts of stained smears were performed. Both, erythrocytopoiesis and granulocytopoiesis showed regeneration, maturation, and an absolute increase of the number of precursors and of mature cells. The quantitative data obtained in vitro during 24 hs correspond with our data of kinetics obtained by observed mitotic duration and cell differential countings in vivo. However, after a longer cultivation time we found a diminution of divisible precursors, and an increase of mature erythroblasts as well as an excessibe survival of the PMNs.