Morphodifferentiation and Structure of Hertwig's Root Sheath in the Cat

The epithelial root sheath in the cat is a multilayered structure that consists of confluent outer and inner epithelial strata enclosing a central layer of cells, which are morphologically like those of the stratum intermedium. A continuous PAS-positive membrane separates the epithelial structure from the developing pulp. On the dental sac surface, the basement membrane is discontinuous, and even absent in some regions. This situation remains until the root and cementum are completely formed.