normal and pathological mineralization in vertebrates but also with the
interesting problems involved in the formation of in- tracellular
deposits of calcium oxalate in plants. Here cal- cium carbonate and
silica may also be involved in the mineral- ization processes. Calcium
carbonate is an important component in the formation of mollusc and
avian shells. The observation that both calcite and aragonite may be
formed in biogenic cal- cium carbonate raises important questions as to
what factors control the formation of the final mineral phase. There is
little doubt that thermodynamically less stable phases may be
kinetically stabilized for long periods of time by other mole- cules
present in vivo. In normal mineralization, calcium salts may initially
be deposited both within the cells and extracel- lularly. In the latter
case, the role of matrix vesicles and the ways in which the matrix
components might control mineral- ization were especially emphasized.
There is clearly a need for more structural and functional information
involving cells, matrix components, and their associated crystals. The
develop- ment of further techniques involving mutants, chromofluors, and
fixatives for preservation of tissue and the ions present in vivo was
recommended. In dealing with abnormal and pathological mineralization,
the Workshop concentrated on urolithiasis, gout and pseudo-gout, and the
formation of dental caries. Discussions based on the influence of media
of low pH on mineral surfaces highlighted some of the factors of
importance in controlling crystal dis- solution.