Failure to detect crystalline brushite in embryonic chick and bovine bone by X-ray diffraction.

We have reexamined the question of whether brushite (CaHPO4 X 2H2O) occurs in embryonic bone. On the basis of the experiments reported here, and a reexamination of data previously obtained in this laboratory, we have concluded that crystalline brushite as a separate phase identifiable by X-ray diffraction does not occur in embryonic chick or bovine bone. Crystalline brushite previously identified in this laboratory in the less-mineralized fractions of embryonic chick bone was apparently formed artifactually during the fractionation process, possibly from preexisting domains of HPO4(-2) groups in a noncrystalline brushite-like configuration.