The stratum intermedium in a developing tooth

Tooth development

Tooth development or odontogenesis is the complex process by which teeth form from embryonic cells, grow, and erupt into the mouth. Although many diverse species have teeth, non-human tooth development is largely the same as in humans...

 is a layer of two or three cells between the inner enamel epithelium

Inner enamel epithelium

The inner enamel epithelium, also known as the internal enamel epithelium, is a layer of cells located on the rim nearest the dental papilla of the enamel organ in a developing tooth. This layer is first seen during the bell stage....

 and the newly forming cells of the stellate reticulum

Stellate reticulum

The stellate reticulum is a group of cells located in the center of the enamel organ of a developing tooth. These cells are star shaped and synthesize glycosaminoglycans. As glycosamingoglycans are produced, water is drawn in between the cells and stretch them apart...

. It first appears during the early bell stage of tooth development, at around the 14th week of intrauterine life. The stratum intermedium has a notably high alkaline phosphatase

Alkaline phosphatase

Alkaline phosphatase is a hydrolase enzyme responsible for removing phosphate groups from many types of molecules, including nucleotides, proteins, and alkaloids. The process of removing the phosphate group is called dephosphorylation...

 activity. This layer, along with the inner enamel epithelium, is responsible for the tooth enamel

Tooth enamel

Tooth enamel, along with dentin, cementum, and dental pulp is one of the four major tissues that make up the tooth in vertebrates. It is the hardest and most highly mineralized substance in the human body. Tooth enamel is also found in the dermal denticles of sharks...

 formation

Amelogenesis

Amelogenesis is the formation of enamel on teeth and occurs during the crown stage of tooth development after dentinogenesis, which is the formation of dentine. Although dentine must be present for enamel to be formed, it is also true that ameloblasts must be present in order for dentinogenesis to...

. It is a part of the dental (enamel) organ.