Weinstock M, Leblond C P
J Cell Biol. 1974 Jan;60(1):92-127. doi: 10.1083/jcb.60.1.92.
The elaboration of dentin collagen precursors by the odontoblasts in the incisor teeth of 30-40-g rats was investigated by electron microscopy, histochemistry, and radioautography after intravenous injection of tritium-labeled proline. At 2 min after injection, when the labeling of blood proline was high, radioactivity was restricted to the rough endoplasmic reticulum, indicating that it is the site of synthesis of the polypeptide precursors of collagen, the pro-alpha chains. At 10 min, when the labeling of blood proline had already declined, radioactivity was observed in spherical portions of Golgi saccules containing entangled threads, and, at 20 min, radioactivity appeared in cylindrical portions containing aggregates of parallel threads. The parallel threads measured 280-350 nm in length and stained with the low pH-phosphotungstic acid technique for carbohydrate and with the silver methenamine technique for aldehydes (as did extracellular collagen fibrils). The passage of label from spherical to cylindrical Golgi portions is associated with the reorganization of entangled into parallel threads, which is interpreted as the packing of procollagen molecules. Between 20 and 30 min, prosecretory and secretory granules respectively became labeled. These results indicate that the cylindrical portions of Golgi saccules transform into prosecretory and subsequently into secretory granules. Within these granules, the parallel threads, believed to be procollagen molecules, are transported to the odontoblast process. At 90 min and 4 h after injection, label was present in predentin, indicating that the labeled content of secretory granules had been released into predentin. This occurred by exocytosis as evidenced by the presence of secretory granules in fusion with the plasmalemma of the odontoblast process. It is proposed that pro-alpha chains give rise to procollagen molecules which assemble into parallel aggregates in the Golgi apparatus. Procollagen molecules are then transported within secretory granules to the odontoblast process and released by exocytosis. In predentin procollagen molecules would give rise to tropocollagen molecules, which would then polymerize into collagen fibrils.
通过电子显微镜、组织化学和放射自显影技术，在静脉注射氚标记的脯氨酸后，对30 - 40克大鼠切牙成牙本质细胞中牙本质胶原前体的合成过程进行了研究。注射后2分钟，当血液中脯氨酸的标记率很高时，放射性仅限于粗面内质网，这表明它是胶原多肽前体即前α链的合成部位。注射后10分钟，当血液中脯氨酸的标记率已经下降时，在含有缠结细丝的高尔基囊泡的球形部分观察到放射性，并且在注射后20分钟，放射性出现在含有平行细丝聚集体的圆柱形部分。这些平行细丝长度为280 - 350纳米，用低pH值磷钨酸技术检测碳水化合物时呈阳性，用亚甲胺银技术检测醛基时也呈阳性（细胞外胶原纤维也是如此）。标记物从球形高尔基部分向圆柱形部分的转移与缠结细丝重新排列成平行细丝有关，这被解释为原胶原分子的组装。在20到30分钟之间，前分泌颗粒和分泌颗粒分别被标记。这些结果表明，高尔基囊泡的圆柱形部分转变为前分泌颗粒，随后转变为分泌颗粒。在这些颗粒内，被认为是原胶原分子的平行细丝被运输到成牙本质细胞突起。注射后90分钟和4小时，前期牙本质中出现标记物，这表明分泌颗粒中的标记物内容物已释放到前期牙本质中。这是通过胞吐作用发生的，融合的分泌颗粒与成牙本质细胞突起的质膜存在证明了这一点。有人提出，前α链产生原胶原分子，这些分子在高尔基装置中组装成平行聚集体。然后，原胶原分子在分泌颗粒内被运输到成牙本质细胞突起，并通过胞吐作用释放。在前期牙本质中，原胶原分子将产生原胶原蛋白分子，然后这些分子将聚合成胶原纤维。
