The stratum intermedium in a developing tooth is a layer of two or three cells between the inner enamel epithelium and the newly forming cells of the stellate reticulum. It first appears during the early bell stage of tooth development, at around the 14th week of intrauterine life (in humans). The stratum intermedium has a notably high alkaline phosphatase activity. This layer, along with the inner enamel epithelium, is responsible for the tooth enamel formation. It is a part of the dental (enamel) organ. [ http://en.wikipedia.org/wiki/Stratum_intermedium ]