An electron-microscopic observation on the collagen fibril arrangement in the outermost layer of dog dentine as revealed by tangential sections.

In the forming initial dentine, each odontoblast extended a thick process perpendicularly to the basal lamina, and the collagen fibrils formed were divided into two groups based on their orientation. One was a group of fibrils running parallel to an odontoblastic process to organize the peri-process fibril bundles to organize the inter-process fibril bundles. This pattern of fibril orientation was similar in both crown and root. The diameter of each collagen fibril ranged from 30-100 nm in the crown and from 30-180 nm in the root.