[Stromal cells of the regenerating bone marrow in rats (an immunocytochemical electron microscopy study)].

Process of the bone marrow regeneration has been studied after its removal out of the rat femoral bone cavity. The stage of stroma formation precedes hemopoiesis. The stromal cells during its reconstruction (the 4th-5th day after removal of the bone marrow) are analyzed by means of the indirect immune-peroxidase electron microscopical method with antiserum applied against insoluble antigens of the rat bone marrow cells. Most of the stromal cells do not fix the antiserum used, as do the hemopoietic cells, macrophages and preosteoclasts. Some part of the stromal cells (not more than 30%) demonstrate the immune-peroxidase label. The labelled stromal cells have some ultrastructural signs of poorly differentiated elements of fibroblastic and osteoblastic raws. In the regeneration area, there are non-labelled poorly differentiated cells, which do not differ, at the ultrastructural level, from labelled poorly differentiated stromal elements. Possible causes of the difference revealed among the poorly differentiated stromal cells concerning their fixing of the anti-bone-marrow antiserum are discussed.