Activity of gamma-glutamyl transferase in developing teeth of the rat.

gamma-Glutamyl transferase activity was studied with an enzyme histochemical technique in rat molar teeth at different stages of development. The odontoblasts showed an increasing activity during formation of the crown. The secretory ameloblasts did not show any activity, while activity was intense in the postsecretory ameloblasts. This activity was confined to the apical part of the cell. In the reduced ameloblasts at the enamel free cusp tips a similar activity was noted. Since gamma-glutamyl transferase has been shown to be involved in endocytosis and transport of amino acids, the localization of the enzyme in developing teeth suggests an active uptake of amino acids from the enamel matrix of the ameloblasts during enamel maturation.