Interrod enamel has the same composition as enamel rod, however a histologic distinction is made between the two because crystallite orientation is different in each. The border where the crystallites of enamel rods and crystallites of interrod enamel meet is called the rod sheath.

Striae of Retzius are incremental lines that appear brown in a stained section of mature enamel. These lines are composed of bands or cross striations