text: <unk>  is histologically identified on microscopic views of tooth<unk> .  Because<unk>  is located around<unk>  rods, the areas of<unk>  enhances the "keyhole" appearance of<unk>  rods by acting as its border.  The location where the two areas of<unk>  meet is known as the rod sheath.
  All tooth<unk> , including<unk>  and<unk>  rods, is made by ameloblasts.  However,<unk>  is formed slightly sooner than<unk>  rods.<unk>  has the same composition as<unk>  rods.  A distinction is made between the two because they differ in the direction of their crystalline patterns.
option_0: Interrod enamel
option_1: Agar plate
option_2: Demegestone
option_3: Mees' lines
option_4: Nodule of vermis
option_5: Clavicle
option_6: Articular processes
option_7: Half and half nails