A Review of Bone Cell and Substratum Interactions - an Illustration of the Role of Scanning Electron-Microscopy

The first experimental studies concerning observations of changes in bone cell functional morphology were made using the SEM, and SEM has remained paramount in this field. Bone forming and resorbing cells only exist on surfaces – which are available for study after removal of adjacent tissue layers: The underlying matrix surface can then be studied after removal of the cells, and the mineral front examined after removing the matrix (with an appropriate solvent or by plasma ashing). In this review, we analyse the main findings which we have made in this laboratory concerning the biological activities of osteoblasts (bone forming cells) and osteoclasts (bone resorbing cells). The technical problems of specimen preparation of cells which shrink more than the substrate to which they are attached have been convered previously (Boyde et al. 1977). Such problems obviously affect the lateral, cell to cell inter-relationships more than the cell to substrate effects which we cover here. At present, we can conclude that SEM has made a major contribution to bone biology by permitting observation of normal cells and natural and surrogate substrates. We confidently predict that it will continue to play a pivotal role in the closer observation of cell-cell-substrate interactions particularly in respect of local hormonal effects, as well as in bone pathology and implantology.