Heritier M, Fernandez J P
J Biol Buccale. 1981 Dec;9(4):319-34.
The structure and ultrastructure of Hertwig's sheath have been studied in the mice on molar tooth germs collected on day 16. On a morphological basis, two parts, a diaphragm portion and a sheath part could be described. The diaphragm portion consisted of two layers, one internal and one external with in between occasionally cells disposed in quincunx. Mitotic activity was noted in the external layer. This fact raised the possibility of the existence of a cellular flow from this layer towards the internal counterpulpal layer. The permanent existence of the sheath during root elaboration could thus be explained. In the internal layer structural modifications and cell axis variations seemed to be related to the odontoblast differentiation. In the "sheath" part electron microscopy revealed the existence of a fine layer of unmineralized collagen fibrils which remained under the internal epithelial layer. The observations related to the structure of the periradicular sheath cells questioned the hypothesis whether these cells assume secretory potentials.
在第16天收集的小鼠磨牙牙胚上，对赫特维希上皮根鞘的结构和超微结构进行了研究。基于形态学，可将其描述为两个部分，即隔膜部分和鞘部分。隔膜部分由两层组成，一层内部层和一层外部层，两层之间偶尔有呈梅花形排列的细胞。在外层观察到有丝分裂活性。这一事实增加了从该层向内部反髓腔层存在细胞流动的可能性。因此，可以解释在牙根发育过程中鞘的永久存在。在内层，结构改变和细胞轴变化似乎与成牙本质细胞分化有关。在“鞘”部分，电子显微镜显示在内侧上皮层下方存在一层未矿化的细胶原纤维。与根尖周鞘细胞结构相关的观察结果对这些细胞是否具有分泌潜能的假设提出了质疑。
