[Hematopoietic stroma and the regulation of hematopoiesis in extramedullary bone marrow transplants in mice].

The bone marrow fragments were transplanted under the renal capsule and "stromal function" of the transplants during up to 1.5 years was estimated by the numbers of CFU-S, myelokaryocytes and the weight of newly formed bone tissue. On the basis of the published and authors' data, a conclusion was drawn that the ability of the stromal precursor cells of bone marrow to provide for the growth of hemopoietic territories is limited by the size of medullary cavity; outside its limits this ability is not only realized, but may be additionally stimulated by some distant factors (preirradiation of the recipients in the given case). The self-maintenance ability of the stromal mechanocytes from the old mice during 43 months was shown by means of retransplantation. On the basis of electron microscopy and published data, a suggestion was put forward that fibroblastic reticular cells might be ancestral elements of osteogenic differentiation.