Predentine and mineralization (200X)

This image focuses on the dentine and pulp. The tissue closest to the odontoblast layer is the predentine. It stains lighter than the dentine that resides above it. The predentine is yet to be mineralized. There are numerous round structures called calcospherites within the predentine that stains like the dentine. They will eventually increase in size and fuse making up the main body of the dentine of the tooth (the globular dentine). If this happens too fast, the fusing process will not complete entirely and we'll get what is called interglobular dentine.

Put simply, one can say that the globular dentine is fully mineralized while the interglobular dentine is not.