Phase microscopic observations of rat incisor enamel

Thin ground sections (4–10 μ) of rat incisor enamel were prepared in appropriate planes using a modified hand grinding technique. Phase microscopic observations of these sections confirmed the previously defined rod arrangement in the inner layer of enamel, and also demonstrated a high degree of structural orientation in the outer layer of enamel. The initial layer of enamel formed was found to present a morphologic picture which has not been previously defined: a series of inter‐connected pillars of enamel on an elevated base which has a “fish net” appearance in tangential section.