Yamamoto H, Sasaki J, Matsuura J, Nomura T, Sato E F, Shimokawa H, Ishizeki K, Nawa T
Department of Oral Anatomy, School of Dentistry, Iwate Medical University, Morioka, Japan.
Acta Anat (Basel). 1997;160(4):232-8. doi: 10.1159/000148016.
Both the expression of amelogenin mRNA and secretion of amelogenin were investigated in rat molars by in situ hybridization and immunohistochemistry. Probes were designed by multiple-labeling of oligonucleotide probes for in situ hybridization. Amelogenin mRNA first appeared in differentiating ameloblasts of the distal region and some inner enamel epithelial cells of enamel-free area (EFA cells) of the second cusp at postnatal day 0. At the same time, amelogenin protein was detected in the extracellular matrix between dentin and differentiating ameloblasts and in some EFA cells of the second cusp. At postnatal day 1-3, amelogenin was expressed in the secretory ameloblasts, and in the matrix beneath these cells. Both amelogenin mRNA and amelogenin were detected in the EFA cells and their extracellular matrix. After postnatal day 5, amelogenin mRNA and amelogenin were detected in the secretory ameoloblasts and extracellular matrix in the enamel-forming region, respectively. At this time, amelogenin mRNA was not detected in the EFA cells, but a small amount of amelogenin was found in the matrix beneath the EFA cells. These findings suggest that EFA cells differentiate into amelogenin-secreting cells, i.e. ameloblasts, but that the secretion lasts for only a short period at the early stage of tooth development.
通过原位杂交和免疫组织化学方法，对大鼠磨牙中釉原蛋白mRNA的表达和釉原蛋白的分泌进行了研究。原位杂交的寡核苷酸探针通过多重标记设计。出生后第0天，釉原蛋白mRNA首次出现在第二尖牙远中区域正在分化的成釉细胞以及无釉区（EFA细胞）的一些内釉上皮细胞中。与此同时，在牙本质与正在分化的成釉细胞之间的细胞外基质以及第二尖牙的一些EFA细胞中检测到了釉原蛋白。出生后第1 - 3天，釉原蛋白在分泌期成釉细胞及其下方的基质中表达。在EFA细胞及其细胞外基质中均检测到了釉原蛋白mRNA和釉原蛋白。出生后第5天之后，分别在釉质形成区域的分泌期成釉细胞和细胞外基质中检测到了釉原蛋白mRNA和釉原蛋白。此时，在EFA细胞中未检测到釉原蛋白mRNA，但在EFA细胞下方的基质中发现了少量釉原蛋白。这些发现表明，EFA细胞分化为分泌釉原蛋白的细胞，即成釉细胞，但在牙齿发育早期，这种分泌仅持续较短时间。
