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Do Secretory‐Stage Ameloblasts Divide? Experimental Evidence

Our objective is to test the dictum that secretory ameloblasts cannot divide. This idea is often mentioned in dental biology textbooks without citation or evidence; its source seems to be studies of rodent incisors from the 1960's. However, rodent incisors are ever‐growing, and not acceptable models for enamel epithelia function in other mammals. Also, there are two reasons to expect that mature ameloblasts divide. First, recent studies show that tensile forces induce mitosis in epithelia, and it is likely that the enamel epithelium undergoes tension as enamel is deposited and the surface area of the growing crown expands. Second, we now know that ameloblasts are subject to the same biorhythms that synchronize proliferation of osteoblasts. If ameloblast division is similarly coordinated by the nervous system and occurs at night, it is unlikely that it will have been observed since most experimental protocols are carried out during daylight hours.