the ameloblast cell become longer and the nucleus migrates towards the proximal end.In contrast to this, golgi apparatus and centrioles migrate towards the distal end.This change is referred to as "REVERSAL OF POLARITY" .During this stage odontoblast starts laying down dentin. Reversal of Nutrition- as long as the ameloblast is in contact with the dental papilla it receives nutrient material from the blood vessels of the tissue but due to formation of this dentin the original source of nutrition is cut off and ameloblast is supplied by capillaries penetrating the outer enamel epithelium. This change in nutrition source is referred to as reversal of nutrition. 3. Formative Stage In this stage formation of enamel matrix begins during the formation of enamel matrix the ameloblast retain approximately the same length. 4. Maturative Stage After the formation of enamel matrix mineralisation of enamel takes place which is known as maturation. During this stage the ameloblasts are slightly reduced in length. The stratum intermedium cells lose their cuboidal shape and assumed to be as spindle shape. During this stage ameloblasts also exhibits microvilli at their distal extremities. 5. Protective Stage In this stage enamel is completely developed and fully calcified. Now the cell layers forms a stratified epithelial covering of enamel which is known as reduced enamel epithelium. This reduced enamel epithelium protects the mature enamel. 6. Desmolytic Stage In this stage the reduced enamel epithelium proliferates and induce atrophy. The reduced enamel epithelium releases enzymes which destroy the connective tissue this process is known as desmolysis. Function Ameloblasts are cells which secrete the enamel proteins enamelin and amelogenin which will later mineralize to form enamel, the hardest substance in the human body. Ameloblasts control ionic and organic compositions of enamel. It is theorized that a circadian clock (24-hour) probably regulates enamel production on a daily cycle by the ameloblasts (similar to osteoblasts in production of bone tissue). Ameloblasts adjust their secretory and resorptive activities to maintain favorable conditions for biomineralization. Clinical significance These cells are sensitive to their environment. One common example is illustrated by the neonatal line, a pronounced incremental line of Retzius found in the primary teeth and in the larger cusps of the permanent first molars, showing a disruption in enamel production when the person is born. High fevers in childhood are also an example of bodily stressors causing interruptions in enamel production. Another possible example of this sensitivity