Electron microscopy of biochemically characterized, newly secreted tooth enamel proteins.

The protein complex of developing tooth enamel is a unique product of biological synthesis in vertebrates, and its role in enamel mineralization is unknown. Using simple methods, molecular aggregates and polycrystalline deposits from purified extracts of the total protein complex and a 21-20 kDa component were discovered and compared with sectioned material. The size and conformation of the aggregates correspond closely with the morphology of the so-called stippled material found adjacent to the secreting ameloblasts in sectioned electron-microscopic preparations. For the first time, polycrystalline deposits, with electron-diffraction characteristics identical to those obtained from the purified extracts, were also obtained from the newly secreted enamel surface of freshly extracted developing porcine teeth by a simple direct sampling method.