CHANGES IN THE STRUCTURE OF BONE-MARROW M ICROENVIRONMENT ELEMENTS INMYELODYSPLASTIC SYNDROMES

The data of histological and ultrastructural studies on bone marrow he mopoietic microenvironment of 27 patients with different types of myel odysplasias are given. In all cellular stromal elements intranuclear b odies are found. Morphologic features have been described which might testify to the changes in rRNA-synthesizing activity of the nucleolar apparetus in endosteal and perivascular cells. Changes in the intramed ullar extracellular matrix are also established. On the basis of the d ata presented one may suggest, that one of the pathogenetic factors co ntributing to disorders of proliferation and differentiation of hemopo ietic cells might be the defects in the microenvironment.