136: Ultrastructural analysis of growth zone architecture. A SEM study in rats

Abstract

In the present study the architecture of the growth zone and its disturbance in various forms of metabolic bone disease were investigated. Epipyhses and metaphyses of rats were separated transversely by fracture or sectioned longitudinally. The specimens were prepared by critical point drying or (for the study of mineralized structures) by digestion with sodium hypochlorite. A stable functional system of epipyhseal bone plate growth cartilage and metaphyseal trabeculae is formed in a light weight construction by various collagen fiber systems, cell columns and a framework of calcified cartilage matrix. Individual cell columns are joined with the epipyhses by being inserted into holes of the lower surface of the epiphyseal bone plate. The columns are stabilized by a shroud like system of collagen fibers and connected with one another by other interchanging fiber systems. Other fibers run longitudinally into the metaphyseal bone. In the zone of calcification mineralized globules can be found within longitudinal and transverse septa, whereas the matrix plane in contact with the chondrocyte cell surface shows only a fine granular surface. It can be shown that metabollically induced disturbance of longitudinal growth (rickets, uremia) will distroy this functional system.