Immunohistochemical studies on the differentiation of ameloblasts and odontoblasts and the interrelationship between them.

为了研究成釉细胞在发育早期的釉质蛋白的合成和分泌，我们利用初步实验中产生的单克隆抗体在光镜和电镜水平上进行了免疫组织化学定位。材料为大鼠出生后1 ~ 5天的下颌第一磨牙牙胚。双向电泳后的免疫印迹分析显示，所用单克隆抗体的抗原分子为26 kDa的amelogenin （PI, 5-6）。使用该单克隆抗体的免疫组织化学检查表明，在分化的早期阶段，前成釉细胞既可以合成成釉原蛋白，也可以通过经典的分泌途径分泌成釉原蛋白。在一些成釉前细胞和成釉细胞中，我们观察到内质网池的扩张，显示出异质免疫标记。前牙本质及成釉细胞和牙乳头细胞间隙也检测到免疫标记，表明成釉原蛋白从成釉细胞层渗透到牙乳头。成牙细胞质膜上靠近牙釉质蛋白的包被凹坑的存在以及成牙细胞溶酶体的免疫标记表明牙釉质蛋白被吞噬进入成牙细胞。这些观察结果表明，牙釉质蛋白对包括成牙细胞在内的牙乳头的渗透在成釉细胞和成牙细胞之间的相互作用中起作用。应用抗大鼠淀粉原蛋白单克隆抗体En3在光镜和电镜下观察1 ~ 4日龄大鼠下颌第一磨牙无牙釉质区，以明确无牙釉质区是否存在牙釉质缺失。虽然分泌前成釉细胞样细胞（PALCS）没有极化，但在PALCS和牙本质之间的界面上检测到几乎连续的淀粉原蛋白免疫荧光。免疫电镜检查也显示高尔基体和PALCs分泌囊泡以及PALCs与牙本质之间的无定形物质层呈阳性标记。这些结果表明，无牙釉质区PALCs合成并分泌淀粉原蛋白，淀粉原蛋白向牙髓的渗透可能在无牙釉质区PALCs与成牙细胞相互作用和/或前牙本质矿化的启动中起作用。少

In order to examine the synthesis and secretion of enamel protein by ameloblasts in their early stages of development, immunohistochemical localization was carried out at light and electron microscopic levels using a monoclonal antibody produced in a preliminary experiment. Materials used were tooth germs of mandibular first molars of rats at 1-5 days after birth.Immunoblotting analysis after two-dimensional electrophoresis revealed that antigen molecules of the monoclonal antibody used were amelogenin of 26 kDa(PI, 5-6). An immmunohistochemical examination using this monoclonal antibody demonstrated that the preameloblasts in their early stages of differentiation both synthesized amelogenin and secreted through a classical merocrine secretory pathway. In some preameloblasts as well as ameloblasts we observed the distended cisternae of rER which demonstrated heterogenous immunolabelling. The immunolabellings were also detected in the predentin as well as the intercellular spaces of odo … More ntoblasts and dental papilla cells which indicated penetration of amelogenin from the ameloblast layer to the dental papilla. The presence of coated pits at the plasma membrane of odontoblasts in close proximity to enamel protein along with the immunolabelling of lysosome of the odontoblasts suggest the phagocytosis of the enamel protein into the odontoblasts. These observations indicate that the penetration of enamel protein toward dental papilla including odontoblasts plays a role in the interaction between ameloblasts and odontoblasts.The enamel-free area of 1-4 day-old rat mandibular first molars were investigated using the monoclonal antibody En3 against rat amelogenin at light and electron microscopic levels in order to clarify whether the enamel-free area is virtually devoid of enamel. Although the presecretory ameloblast-like cells(PALCS)were not polarized, almost continuous immunofluorescence for amelogenin was detected at the interface between PALCs and dentin. Immunoelectron microscopic examination also revealed the positive labelling in the Golgi apparatus and secretory vesicles in PALCs and in the layer of amorphous materials between PALCs and dentin. These results suggest that PALCs at enamel-free area synthesize and secrete amelogenin the penetration of which toward the dental pulp might play a role in the interaction between PALCs and odontoblasts in the enamel-free area and/or the initiation of mineralization of predentin. Less