Ameloblast

AMELOBLAST (from Old English aethe-enamel and Greek blastos-bud), synonym adamantoblast, ganoblast, cell of the inner epithelium of the enamel organ, participating in the formation of enamel; Ameloblasts have a cylindrical-prismatic shape (height 40-50 μ, diameter 6-7 μ); an oval nucleus, 10-12 μ long, contains 2-3 nucleoli and is located along the longitudinal axis of the cell at that pole which is adjacent to the intermediate layer of the enamel organ. In the fine-grained protoplasm of ameloblasts are found chondriosomes and the cell center; at the time of enamel formation, numerous droplets and granules of pre-enamel are found in the protoplasm. Ameloblasts multiply by mitotic division. At the beginning of enamel formation, the basal ends of ameloblasts somewhat elongate, transforming into the so-called Tomes' processes—the first traces of enamel prisms; from this moment ameloblasts cease to multiply. With the completion of enamel formation, ameloblasts cease to exist as cells, entering into the composition of the tooth cuticle. Ameloblasts represent differentiated cells of the basal layer of the covering epithelium of the oral cavity, which in the early embryonic period (the beginning of this process refers to the 34th day of embryonic life) became immersed in the underlying mesodermal tissue. In rickets, shortening of ameloblasts is noted, which take on rounded outlines, vacuolization of the protoplasm, pyknosis of the nuclei, which results in various irregularities in the structure of enamel.