Kawamoto T, Shimizu M
Department of Biochemistry, School of Dental Medicine, Tsurumi University, Yokohama, Japan.
J Histochem Cytochem. 1997 Feb;45(2):213-30. doi: 10.1177/002215549704500207.
We studied by autoradiography the distribution of 45Ca in the enamel organ of frozen rats 4.3, 6.1, 7.8, 10.6 and 13.7 sec after an i.v. injection. The intercellular junctions of the proximal side of the smooth-ended ameloblast (SA) and the distal side of the ruffle-ended ameloblast (RA) were closed to calcium. The junctions of the distal side of SA, the proximal side of RA, and both sides of the secretory stage ameloblasts were not. The time required for calcium to pass through the ameloblast layer was less than 1.8 sec in the secretory stage and SA region. The time in the RA region was 3.5-6.3 sec. In the transitional region from RA to SA, a band of strong radioactivity appeared from the papillary layer of RA region towards the enamel of the SA region. The radioactivity in the secretory stage enamel increased almost linearly with time. The diffusion speed of calcium in the enamel was more than 50 microns for 1.8 sec in the maturation stage and less than 15 microns for 9.4 sec in the secretory stage. These results indicate that in the secretory and SA regions calcium moves to the enamel surface through the intercellular spaces of ameloblasts and in the RA region via RA cells.
我们通过放射自显影术研究了静脉注射后4.3、6.1、7.8、10.6和13.7秒时冷冻大鼠牙釉质器官中45Ca的分布。平滑末端成釉细胞（SA）近端和皱褶末端成釉细胞（RA）远端的细胞间连接对钙是封闭的。SA远端、RA近端以及分泌期成釉细胞两侧的连接则不是。在分泌期和SA区域，钙穿过成釉细胞层所需的时间少于1.8秒。在RA区域，这个时间为3.5 - 6.3秒。在从RA到SA的过渡区域，从RA区域的乳头层向SA区域的牙釉质出现了一条强放射性带。分泌期牙釉质中的放射性几乎随时间呈线性增加。在成熟阶段，钙在牙釉质中的扩散速度在1.8秒内超过50微米，在分泌期9.4秒内则小于15微米。这些结果表明，在分泌期和SA区域，钙通过成釉细胞的细胞间隙移动到牙釉质表面，而在RA区域则通过RA细胞移动。
