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合成和分泌成釉蛋白的情况，用初步实验中制备的单抗在光镜和电子显微镜水平上进行了免疫组织化学定位。实验材料为出生后1~5天的大鼠下颌第一磨牙牙胚，双向电泳法免疫印迹分析表明，所用单抗的抗原分子为26 kDa的釉原蛋白(pI，5-6)。用该单抗进行免疫组织化学检测表明，分化早期的前成釉细胞既合成了釉原蛋白，又通过经典的内分泌分泌途径进行分泌。在一些前成釉细胞和成釉细胞中，我们观察到了扩张的RER池，这表明了异源免疫标记。在前牙本质和odo…的细胞间隙中也检测到免疫标记。成釉细胞和牙乳头细胞较多，表明成釉蛋白从成釉细胞层向牙乳头渗透。成牙本质细胞质膜上靠近釉质蛋白的包被凹坑的存在，以及成牙本质细胞溶酶体的免疫标记，提示成牙本质细胞吞噬了釉质蛋白。这些观察结果表明，釉质蛋白对包括成牙本质细胞在内的牙乳头的渗透在成釉细胞和成牙本质细胞之间的相互作用中起着重要作用。本研究用抗大鼠釉原蛋白的单抗EN3对1-4日龄大鼠下颌第一磨牙无釉质区进行了光镜和电子显微镜观察，以明确无釉质区是否实质上没有釉质。尽管记忆前的成釉细胞样细胞(PALCs)未被极化，但在PALCs与牙本质的交界处可检测到几乎连续的成釉细胞蛋白免疫荧光。免疫电子显微镜显示，PALCs高尔基体、分泌小泡以及PALCs与牙本质之间的无定形物质层均有阳性标记。这些结果提示，无釉质区域的PALCs合成和分泌釉原蛋白，其对牙髓的穿透可能在PALCs与无釉质区域的成牙本质细胞相互作用和/或启动前牙本质矿化过程中发挥作用。较少

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