Prostak K, Seifert P, Skobe Z
Department of Electron Microscopy, Forsyth Dental Center, Boston, Massachusetts 02115.
Am J Anat. 1990 Sep;189(1):77-91. doi: 10.1002/aja.1001890110.
Ultrastructural alterations induced by colchicine were investigated to determine the secretory activities of odontogenic cells during formation of tooth enameloid matrix in skates. Treated skate inner dental epithelial (IDE) cells did not display dilated cisternae of the granular endoplasmic reticulum (GER) nor accumulate Golgi-associated secretory granules at any dose level or time interval examined. This response was markedly different from that observed in teleost IDE cells synthesizing the enameloid collagen matrix. Treated skate IDE cells did show increased accumulations of glycogen-containing vesicles and intercellular glycogen associated with amorphous material, compared to controls. Additionally, the aberrant occurrence of large intracellular glycogen pools and amorphous material suggested that carbohydrate processing was a major function of skate IDE cells. Treated odontoblasts associated with enameloid matrix formation sometimes showed dilated GER cisternae, but procollagen secretory granules were not observed. Instead, electron dense material was present within the Golgi cisternae, tubular granules, and large granules. Some electron-dense material appeared to be shunted to a resorptive pathway via multivesicular bodies in treated odontoblasts. The continuity of tubular granules with the enameloid matrix suggested that they contained precursors of the enameloid matrix, and possibly the periodic, 17.5-nm cross-striated, "giant" fibers. Treated odontoblasts associated with predentin collagen matrix deposition showed dilated GER cisternae and accumulations of procollagen secretory granules, features consistent with the function of active collagen synthesis and secretion. The findings indicate that (1) skate IDE cells do not synthesize enameloid collagen as found in bony fish tooth development; (2) skate IDE cells do process glycogen for secretion into the enameloid matrix; (3) collagen, although present, is not a major constituent of skate enameloid matrix; (4) enameloid "giant" fibers are unique to elasmobranchs; and (5) odontoblasts synthesize and secrete proteins other than collagen into the enameloid matrix.
研究了秋水仙碱诱导的超微结构变化，以确定鳐鱼牙釉质样基质形成过程中成牙细胞的分泌活动。在任何剂量水平或所检查的时间间隔内，经处理的鳐鱼内牙上皮（IDE）细胞均未显示颗粒内质网（GER）的扩张池，也未积累与高尔基体相关的分泌颗粒。这种反应与在合成牙釉质样胶原基质的硬骨鱼IDE细胞中观察到的反应明显不同。与对照组相比，经处理的鳐鱼IDE细胞确实显示出含糖原囊泡和与无定形物质相关的细胞间糖原积累增加。此外，大的细胞内糖原池和无定形物质的异常出现表明碳水化合物加工是鳐鱼IDE细胞的主要功能。与牙釉质样基质形成相关的经处理的成牙本质细胞有时显示GER池扩张，但未观察到前胶原分泌颗粒。相反，在高尔基池、管状颗粒和大颗粒内存在电子致密物质。在经处理的成牙本质细胞中，一些电子致密物质似乎通过多泡体被分流到吸收途径。管状颗粒与牙釉质样基质的连续性表明它们含有牙釉质样基质的前体，可能还有周期性的、17.5纳米横纹的“巨型”纤维。与前期牙本质胶原基质沉积相关的经处理的成牙本质细胞显示GER池扩张和前胶原分泌颗粒积累，这些特征与活跃的胶原合成和分泌功能一致。研究结果表明：（1）鳐鱼IDE细胞不像硬骨鱼牙齿发育那样合成牙釉质样胶原；（2）鳐鱼IDE细胞确实加工糖原以分泌到牙釉质样基质中；（3）胶原虽然存在，但不是鳐鱼牙釉质样基质的主要成分；（4）牙釉质“巨型”纤维是板鳃亚纲动物特有的；（5）成牙本质细胞合成并向牙釉质样基质中分泌除胶原以外的蛋白质。
