Slavkin H C, Mino W, Bringas P
Anat Rec. 1976 Jul;185(3):289-312. doi: 10.1002/ar.1091850304.
The incorporation of 3H-tryptophan into the inner enamel epithelium of newborn mouse incisor tooth organs has been studied in situ by light and electron microscopic autoradiography to determine the sites and kinetics of biosynthesis, migration, and secretion of precursor enamel protein during newborn mouse incisor tooth formation maxillary and mandibular incisor tooth amelogenesis was studied 5, 30, 60, 120, 240 minutes and 24 hours following the intraperitoneal injection of 3H-tryptophan. By 5 minutes, 40% of the total silver grains associated with the secretory ameloblasts were localized over the rough endoplasmic reticulum and 50% of the silver grains were localized over the Golgi apparatus. By 30 minutes, silver grains were observed predominately over condensing vacuoles and secretory granules within the forming Tomes' processes, and were also localized over the extracellular "granular" pre-enamel matrix. The enamel proteins were synthesized on membrane-bound polysomes, transferred within the cisternae of the rough endoplasmic reticulum and then accumulated in the inner saccules of the Golgi apparatus. The enamel proteins were than packaged in condensing vacuoles which subsequently became secretory granules which migrated to the lateral and apical secretory regions of the forming Tomes' processes. It was concluded from these in vivo studies that enamel protein were synthesized and subsequently secreted within 30 minutes. The initially secreted precursor enamel protein was localized over a material which demonstrated a granular or stippled ultrastructure. The labeled protein then was localized over the amorphous enamel matrix per se which contained the forming calcium hydroxyapatite crystals. We assumed, therefore, that there are two different ultrastructural forms of 3H-tryptophan containing extracellular enamel proteins and suggest that the granular or "stippled" form represents newly secreted precursor enamel protein.
通过光镜和电镜放射自显影原位研究了新生小鼠切牙牙器官内3H-色氨酸掺入内釉上皮的情况，以确定新生小鼠切牙形成过程中前体釉质蛋白生物合成、迁移和分泌的部位及动力学。在腹腔注射3H-色氨酸后5、30、60、120、240分钟和24小时，对上颌和下颌切牙的釉质形成进行了研究。5分钟时，与分泌性成釉细胞相关的银颗粒总数的40%位于粗面内质网上，50%的银颗粒位于高尔基体上。30分钟时，在形成的托姆斯突内的浓缩泡和分泌颗粒上主要观察到银颗粒，并且也位于细胞外“颗粒状”前釉质基质上。釉质蛋白在膜结合核糖体上合成，在内质网池内转运，然后积聚在高尔基体的内囊泡中。釉质蛋白随后被包装在浓缩泡中，这些浓缩泡随后变成分泌颗粒，迁移到形成的托姆斯突的侧面和顶端分泌区域。从这些体内研究得出的结论是，釉质蛋白在30分钟内合成并随后分泌。最初分泌的前体釉质蛋白位于具有颗粒状或点状超微结构的物质上。然后标记的蛋白位于本身含有正在形成的羟基磷灰石晶体的无定形釉质基质上。因此，我们假设含有3H-色氨酸的细胞外釉质蛋白有两种不同的超微结构形式，并认为颗粒状或“点状”形式代表新分泌的前体釉质蛋白。
