Garant P R, Nagy A, Cho M I
J Dent Res. 1984 May;63(5):622-8. doi: 10.1177/00220345840630050301.
The post-secretory portion of the rat incisor enamel organ was prepared for routine transmission electron microscopy and freeze-fracture replication in order to define further the structural surface features of the ruffle-ended ameloblasts. Surface views of the distal plasma membrane of the ruffle-ended ameloblasts revealed a well-developed zonula occludens junction with from six to ten rows of tight junctional strands. Gap junctions were also observed just proximal to the tight junctional strands. The membranes of the ruffled border contained a rich supply of intramembrane particles (IMP). The IMPs were approximately 7 to 8 nm in diameter and preferentially located on the P-face profiles of the membrane. The density of IMPs on the membranes of the ruffled border was higher than that on the lateral borders of the cell. It is suggested that the IMPs of the ruffled border may represent enzymatic proteins in the basal cell membrane of absorptive ameloblasts. In addition, the large, highly-developed zonula occludens appeared structurally capable of sealing the intercellular spaces between the ruffle-ended ameloblasts.
为了进一步明确皱褶缘成釉细胞的结构表面特征，制备了大鼠切牙釉质器分泌后期的样本用于常规透射电子显微镜检查和冷冻断裂复型。皱褶缘成釉细胞远端质膜的表面观察显示，有一个发育良好的紧密连接，有六到十排紧密连接链。在紧密连接链近端也观察到了缝隙连接。皱褶缘的膜含有丰富的膜内颗粒（IMP）。IMP直径约为7至8纳米，优先位于膜的P面轮廓上。皱褶缘膜上IMP的密度高于细胞侧面边界膜上的密度。提示皱褶缘的IMP可能代表吸收性成釉细胞基底细胞膜中的酶蛋白。此外，大的、高度发达的紧密连接在结构上似乎能够封闭皱褶缘成釉细胞之间的细胞间隙。
