[Stromal cells of the bone marrow in growing bone]. / Kletki stromy kostnogo mozga v rastushchei kosti.

By means of electron microscopy, cytochemistry and radioautography with 3H-thymidine, the bone marrow stromal cells have been studied in the zones of endochondral osteogenesis in the rabbit and rat femoral bones. In the stromal cells demonstrating a high alkaline phosphatase activity are distinguished: perivascular, reticular fibroblastic, osteogenic cells. Populations of the perivascular phosphatase-positive cells include poorly differentiated DNA-synthesizing forms, as well as cells with signs of differentiation into stromal fibroblasts. Cleft-like spaces in cytoplasm of the fibroblastic reticular cells are, probably, formed as a result of lymphocyte-like mononuclears passing through. Phagocyting stromal elements are presented by macrophages, having perivascular localization and including into composition of erythroblastic islets. Mononuclear macrophages are revealed also on the surface of osseous trabecules, where they participate in destruction of hemopoetic and osteogenic cells.

[Submicroscopic changes in the capillary cells of an area of osteogenesis during body uptake of lead acetate]. / Submikroskopicheskie izmeneniia v kletkakh kapilliarov zony osteogeneza pri postuplenii v organizm atsetata svintsa.

Ultrastructurometry has revealed that daily entry of lead acetate in a dose of 50-100 mg/kg per body weight for 1-2.5 months increases chromatin condensation in nuclei, promotes swelling and myelin-like degeneration of the mitochondria, hyperplasia of the endoplasmic net, as well as appearance of the "enlightment" zones in the cytoplasm of endotheliocytes and perivascular cells of the capillaries from a metaphyseal zone of the rat femur. These changes are a consequent of the edema of cells and of the decrease in their biosynthetic activity.