Bronckers A L, Bervoets T J, Wöltgens J H
Arch Oral Biol. 1982;27(10):831-40. doi: 10.1016/0003-9969(82)90038-3.
Surface area measurements of cross-sections of M1 and M2 at 1-11 days were related to biochemical parameters for cell proliferation ([3H]-thymidine incorporation) and mineralization (45Ca uptake) and with increase in dry weight. The pre-eruptive development of molar tooth germs was divided into 4 phases which partly reflect the life cycle stages of the ameloblast. In phase 1 (proliferation phase, duration in M2 about 5 days) mitotic activity and increase in total area were great; ameloblasts were undifferentiated or in a pre-secretory state. In phase 2 (differentiation phase, duration 2-3 days) the number of secretory ameloblasts increased and 45Ca uptake started and increased rapidly. At the end of phase 2, crown morphogenesis was completed and cell proliferation ([3H]-thymidine incorporation) became less. In phase 3 (secretion phase, duration 0.5-1 days) all ameloblasts throughout the tooth germ had differentiated into secretory ameloblasts and enamel matrix surface area increased about twice as fast as that of dentine. At the end of phase 3, the surface area of the enamel matrix almost attained its final value. In phase 4 (maturation phase, duration in M1 till first eruption about 2-3 days), post-secretory ameloblasts increased in number and, in contrast to the surface area of the enamel matrix, that of the dentine continued to increase. The fast, linearly increasing total uptake of 45Ca during phase 4 which was attributed to the mineralization of both newly formed dentine and existing maturing enamel was the main cause of the rapid increase in dry weight of the whole tooth germ.
在第1至11天测量M1和M2横截面的表面积，并将其与细胞增殖（[3H] - 胸腺嘧啶核苷掺入）和矿化（45Ca摄取）的生化参数以及干重增加相关联。磨牙牙胚的萌出前发育分为4个阶段，部分反映了成釉细胞的生命周期阶段。在第1阶段（增殖阶段，M2持续约5天），有丝分裂活性和总面积增加很大；成釉细胞未分化或处于分泌前状态。在第2阶段（分化阶段，持续2 - 3天），分泌性成釉细胞数量增加，45Ca摄取开始并迅速增加。在第2阶段结束时，牙冠形态发生完成，细胞增殖（[3H] - 胸腺嘧啶核苷掺入）减少。在第3阶段（分泌阶段，持续0.5 - 1天），整个牙胚中的所有成釉细胞都分化为分泌性成釉细胞，釉质基质表面积的增加速度约为牙本质的两倍。在第3阶段结束时，釉质基质的表面积几乎达到其最终值。在第4阶段（成熟阶段，M1持续到首次萌出约2 - 3天），分泌后成釉细胞数量增加，与釉质基质表面积相反，牙本质的表面积继续增加。第4阶段45Ca的快速、线性增加的总摄取量归因于新形成的牙本质和现有成熟釉质的矿化，这是整个牙胚干重快速增加的主要原因。
