Ichijo T, Yamashita Y, Terashima T
Department of Oral Anatomy, Faculty of Dentistry, Tokyo Medical and Dental University.
Bull Tokyo Med Dent Univ. 1992 Dec;39(4):71-80.
In a series of studies to investigate the structural features of biological crystals, using an electron microscope, we examined the ultrastructure of human enamel crystals at near atomic resolution through the cross and longitudinal sections of the crystals. The materials used for this study were the middle layer of the noncarious enamel from freshly extracted human erupted permanent molars. The small cubes of the enamel were fixed in glutaraldehyde and osmium tetroxide and embedded in epoxy resin using the routine methods. The ultrathin sections were cut with a diamond knife without decalcification. The sections were examined with HITACHI H-500 and H-700 types of transmission electron microscopes operated at 125-200 kV. Each crystal was observed at the initial magnification of 300,000 times and at the final magnification of 10,000,000 times and over. Using this approach, the authors have been able to show the configuration of the hydroxyapatite in the cross and longitudinal sections of the enamel crystals and observe the basic hexagonal pattern of the unit cell viewed down the c-axis. The authors sincerely believe that the electron micrograph shown in this report is the first atomic image to be obtained from a hydroxyapatite crystal from the human enamel, using the sections.
在一系列旨在研究生物晶体结构特征的研究中，我们使用电子显微镜，通过人类牙釉质晶体的横断面和纵断面，以接近原子分辨率的水平对人类牙釉质晶体的超微结构进行了检查。本研究使用的材料是新鲜拔除的人类恒牙非龋性牙釉质的中层。将牙釉质小块用戊二醛和四氧化锇固定，并采用常规方法包埋于环氧树脂中。用金刚石刀切割超薄切片，无需脱钙。切片用日立H - 500型和H - 700型透射电子显微镜在125 - 200 kV下观察。每个晶体在初始放大倍数为300,000倍、最终放大倍数为10,000,000倍及以上的条件下进行观察。通过这种方法，作者得以展示牙釉质晶体横断面和纵断面中羟基磷灰石的结构，并观察沿c轴方向观察到的晶胞基本六边形图案。作者坚信，本报告中所示的电子显微照片是首次使用切片从人类牙釉质的羟基磷灰石晶体获得的原子图像。
