Sawada T, Inoue S
Department of Ultrastructural Science, Tokyo Dental College, Chiba City, Japan.
Cell Tissue Res. 1994 Dec;278(3):563-71. doi: 10.1007/BF00331375.
A characteristic layer containing numerous fibrils is associated with the basement membrane of the inner enamel epithelium during the early stages of odontogenesis. However, its nature is not well understood. In this study, the layer was examined with high-resolution electron microscopy and immuno-histochemical staining. Tooth germs of monkeys (Macaca fuscata) were studied and each fibril in the layer was found to be a tubular structure, 8-9 nm in width, resembling a "basotubule", the tubular structure previously observed in various basement membranes. The space between the fibrils was filled with a network formed by irregular anastomosing strands with an average thickness of 4 nm; these strands resembled the "cords" forming the network in the lamina densa of basement membranes. After immunoperoxidase staining, fine threads immunoreactive for laminin staining were seen winding along the strands of the network, and 1.5-nm wide filaments, immunoreactive for type IV collagen, took the form of a network arrangement. The 5-nm-wide ribbon-like structures associated with the strands were identified as heparan sulfate proteoglycan by immunostaining. These results are similar to those obtained for the cord network of the lamina densa. The "fibrillar layer" therefore represents a highly specialized lamina fibroreticularis of the basement membrane of the inner enamel epithelium, and rich in basotubules.
在牙胚发生的早期阶段，内釉上皮的基底膜与一层含有大量原纤维的特征性层相关联。然而，其本质尚未完全清楚。在本研究中，使用高分辨率电子显微镜和免疫组织化学染色对该层进行了检查。对猕猴（食蟹猴）的牙胚进行了研究，发现该层中的每根原纤维都是管状结构，宽度为8 - 9纳米，类似于“基底微管”，即先前在各种基底膜中观察到的管状结构。原纤维之间的间隙充满了由不规则吻合的细丝形成的网络，这些细丝平均厚度为4纳米；这些细丝类似于在基底膜致密层中形成网络的“索”。免疫过氧化物酶染色后，可见对层粘连蛋白染色有免疫反应性的细丝沿着网络的细丝缠绕，对IV型胶原具有免疫反应性的1.5纳米宽的细丝呈网络排列形式。通过免疫染色确定与细丝相关的5纳米宽的带状结构为硫酸乙酰肝素蛋白聚糖。这些结果与在致密层的索网络中获得的结果相似。因此，“纤维层”代表内釉上皮基底膜的高度特化的纤维网状层，并且富含基底微管。
