Abstract
Observations have been made, using electron microscopy and x-ray diffraction, on the changes in crystal size and shape which occur in developing rodent enamel during mineralization. Small enamel pieces isolated from ground sections of rat molars and incisors were either embedded in methacrylate and sectioned with a diamond knife for electron microscopy, or they were mounted intact on glass fibers in a Debye-Sherrer type powder camera for x-ray diffraction. By either approach it was found that the apatite crystals were very long in the c axis direction from the beginning of enamel mineralization. Morphologically, the early crystals took the shape of extremely thin, long plates arranged in such a manner that there seemed to be little room for any further length-wise growth. It was demonstrated clearly, on the other hand, that the crystals increased in both thickness and width with advancing mineralization. As a result, the thin crystal plates gradually developed into hexagonal rods, which in the most mature enamel examined measured 500 to 600 A in width and 250 to 300 A in thickness.
Full Text
The Full Text of this article is available as a PDF (1.4 MB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- FEARNHEAD R. W. Electron microscopy of forming enamel. Arch Oral Biol. 1961 Aug;4:24–28. doi: 10.1016/0003-9969(61)90073-5. [DOI] [PubMed] [Google Scholar]
- FRANK R. M., SOGNNAES R. F. Electron microscopy of matrix formation and calcification in rat enamel. Arch Oral Biol. 1960 Mar;1:339–348. doi: 10.1016/0003-9969(60)90095-9. [DOI] [PubMed] [Google Scholar]
- FRANK R. Etudes sur l'infrastructure microscopique de l'émail et sur la surface libre coronaire de la dent. SSO Schweiz Monatsschr Zahnheilkd. 1950 Nov;60(11):1109–1121. [PubMed] [Google Scholar]
- GLAS J. E., OMNELL K. A. Studies on the ultrastructure of dental enamel. 1. Size and shape of the apatite crystallites as deduced from x-ray diffraction data. J Ultrastruct Res. 1960 Feb;3:334–344. doi: 10.1016/s0022-5320(60)80020-2. [DOI] [PubMed] [Google Scholar]
- REITH E. J. The ultra structure of ameloblasts from the growing end of rat incisors. Arch Oral Biol. 1960 Oct;2:253–262. doi: 10.1016/0003-9969(60)90067-4. [DOI] [PubMed] [Google Scholar]
- WATSON M. L., AVERY J. K. The development of the hamster lower incisor as observed by electron microscopy. Am J Anat. 1954 Jul;95(1):109–161. doi: 10.1002/aja.1000950105. [DOI] [PubMed] [Google Scholar]
- WATSON M. L. The extracellular nature of enamel in the rat. J Biophys Biochem Cytol. 1960 Jun;7:489–492. doi: 10.1083/jcb.7.3.489. [DOI] [PMC free article] [PubMed] [Google Scholar]