In striae of Retzius , the striae are characterized by

Individual enamel rods are formed by the activity of ameloblasts. Each rod starts at the DEJ and extends as a wavy, continuous column to the surface of the crown. The mineralization process is apparently somewhat dis- continuous and is characterized by alternating phases of high and low activity. Periods of low activity create "rest" lines within the rods. These rest lines, in combination with similar lines in neighbouring rods, form a structure visible in mounted cross-sections of enamel and are named the striae of Retzius. The striae are regions characterized by relatively higher organic content