Cellular calcium distribution in fetal bones studied with K-pyroantimonate |
| |
Authors: | E. H. Burger J. L. Matthews |
| |
Affiliation: | (1) Laboratory of Cell Biology and Histology, University of Leiden, Rijnsburgerweg 10, Leiden, The Netherlands;(2) Baylor University Medical Center, 3500 Gaston Avenue, 75246 Dallas, Texas |
| |
Abstract: | Summary The calcium distribution in cartilage and bone cells during beginning ossification of fetal mouse long bones was studied after fixation with 2% K-pyroantimonate in 1% osmium.In the developing periosteum, the future osteoblasts showed a sparse cation-antimonate precipitate over the cytoplasm. In young osteoblasts the precipitate was accumulated on the mitochondrial membranes and the plasmalemma. Both organelles were sharply outlined by precipitate in the mature osteoblasts at the onset of mineralization. X-Ray microprobe analysis of these organelles demonstrated the presence of both Sb and Ca. In the extracellular compartment, a collagen-associated precipitate with 50 to 60 nm periodicity appeared during osteoblastic differentiation. During the initial phase of matrix mineralization, a random gross precipitate appeared in the matrix and seemed to be accumulated by osmiophilic matrix vesicles while the collagen fibrils lost their precipitate. Subsequently, during the confluent phase of matrix mineralization, the precipitate rapidly disappeared from the cells, leaving them devoid of precipitate once they were surrounded by mineralized matrix. Similar changes were found in the chondrocytes of the growth plate, but cartilage collagen, unlike osteoid collagen, did not bind precipitate. The results indicate that both osteoblasts and calcifying cartilage cells bind calcium prior to matrix mineralization. Bone collagen has strong pyroantimonate binding capacity, but it is not directly involved with initial stages of matrix mineralization, which starts in close association with matrix vesicles. |
| |
Keywords: | Cellular calcium Electron microscopy Osteoblasts Chondrocytes Mineralization |
本文献已被 SpringerLink 等数据库收录! |
|