CIMPARATIVE STUDY OF DENTAL BASEMENT MEMBRANE

1.在猴和大鼠的发育牙中，与内釉上皮基膜相关的一层特征性纤维层是基膜高度特化的纤维网状层，它异常富含基底管，具有10 nm宽的微纤丝样结构。牙乳头细胞突起插入纤维网状板，其表面与许多平行的基管密切相关。通过高分辨率观察，相邻的基底管之间的空间由1.5-3 nm宽的细丝连接，这些细丝垂直于基底管的轴线。这些结果表明，牙乳头细胞的突起通过1.5-3 nm宽的细丝与基小管群相连。免疫组织化学染色显示纤维连接蛋白存在于基底管及突起与基底管之间的间隙中。这一结果表明，这些1.5-3 nm宽的细丝由纤维连接蛋白组成。巴索特…在这项研究中，纤维网状层中有更多的小管，被认为是基底膜结合的微纤维，可能起到锚定装置的作用，沿着基底膜固定牙乳头细胞。已知间充质细胞的这种排列对于发育中的成牙本质细胞的成功分化至关重要。与成熟期成釉细胞有关的基底膜样结构由光板和致密板组成。后者由一个细小的“索状”网组成，它是基底膜的主要组成部分。它与200 NM宽的更松散的脐带网的第三层密切相关。在未脱矿的标本中，致密层的第三层和部分钙化，形成釉质边缘。该特定区域具有较高的电子密度，矿物晶体的大小、形状和排列方式与牙釉质的其余部分不同。此外，矿化似乎正在沿着绳索进行。这些观察表明，这层致密的基底膜是一种高度专业化的基底膜，它通过基底膜本身的一部分矿化来调节成熟期成釉细胞与釉质的牢固结合，基底膜本身成为釉质的一部分。较少

1. In the developing tooth of monkey and rat a characteristic fibrillar layer associated with the basement membrane of inner enamel epithelium was found to be a highly specialized lamina fibroreticularis of the basement membrane which is unusually rich in basotubules, 10nm wide microfibril-like structures. Dental papilla cell processes were inserted into the lamina fibroreticularis and their surface was closely associated with numerous parallel basotubles. With high-resolution observations the space between neighbouring basotubules were bridged by 1.5-3 nm wide filaments running perpendicular to the axis of basotubules. These results indicate that the processes of dental papilla cells are linked to groups of basotubules by mean of 1.5-3nm wide filaments. Immunoperoxidase staining showed the presence of fibronectin along baseotubules as well as within the space between the process and basotubules. This result indicates that these 1.5-3nm wide filaments are composed of fibronectin. Basot … More ubules, thought to be basement membrane-incorporated microfibrils, in the lamina fibroreticularis in this study are likely to function as an anchoring device to immobilize dental papilla cells along the basement membrane. Such an arrangement of mesenchymal cells is known to be crucial for the successful differentiation of odontoblasts in the developing tooth.2. A basement membrane-like structure associated with the maturation stage ameloblasts of the monkey was composed of a lamina lucida and lamina densa. The latter was made up of a fine "cords" network, the major constituent of the basement membrane. It was closely associated with the third layer of a 200nm wide looser cord network. In specimens without demineralization the third layer and a part of the lamina densa were calcified, and it formed the edge of the enamel. The particular area had a higher electron density, and the size, shape, and arrangement of mineral crystals were different from those of the rest of the enamel. Also, mineralization appeared to be proceeding along the cords. These observations indicate that this dense layer is a highly specialized basement membrane which mediates the firm association of maturation stage ameloblasts with the enamel by means of the mineralization of a part of this basement membrane itself which becomes integrated as a part of the enamel. Less