Raman microprobe studies of two mineralizing tissues: enamel of the rat incisor and the embryonic chick tibia

The laser-Raman microprobe developed at the National Bureau of Standards has been applied to the study of the mineralization process in rat incisor enamel and embryonic chick tibia. Cryostat sections were prepared from fresh frozen tissues and allowed to air dry. In these mineralizing tissues two forms of phosphorus compounds have been observed: (1) an inorganic phase identified as apatitic phosphate and (2) an organic phosphate. The distribution of these components from the mineralizing front to regions of higher mineralization has been determined with a spatial resolution of approximately 15 micrometer. The studies suggest the existence of a carbonate, with a Raman band corresponding to that of the mineral huntite, Mg3Ca(CO3)4, and found in regions of low phosphate mineral content.