The rod sheath is an area identified in histologic
sections of a tooth. It is found where enamel rods, the functional
unit of enamel, meet interrod enamel. The crystals of both types
of enamel meet at sharp angles and form the appearance of a
space called the rod sheath. As a result of this space, the
rod sheath consists of more protein (as opposed to minerals)
than other areas of enamel. For this reason, the rod sheath
is characterized as being hypomineralized in comparison to the
rest of the highly mineralized enamel.
Additionally, the rod sheath is attributed
with giving tooth enamel a "fish-scale" appearance
under a microscope when the enamel has been demineralized or
acid-etched.
