Schellens J P, Everts V, Beertsen W
Anat Rec. 1979 Sep;195(1):95-108. doi: 10.1002/ar.1091950108.
During eruption of the mouse incisor part of the periodontal ligament moves along with the tooth in occlusal direction and is degraded in the gingiva, just apically of the junctional epithelium. When studied with the electron microscope some connective tissue cells (fibroblasts) showed disorganization of both nucleus and cytoplasm. In other cells vacuoles were observed containing partly degraded cellular constituents. Sometimes within these vacuoles electron dense material with the appearance of clumped chromatin was observed. On the basis of this observation it is concluded that heterophagocytosis contributes to the process of fibroblast breakdown. The ultrastructure of these heterophagic cells resembled that of fibroblasts. Collagenous fibrils were observed within cytoplasmic vacuoles of fibroblasts indicating that collagen is phagocytosed and probably digested in the lysosomal apparatus. Part of the intercellular space was filled with a homogeneous material of moderate electron density, intermingled with some collagenous fibrils. Within some cells of the junctional epithelium partly degraded material was observed which may indicate that the epithelium contributes to the removal of residual products of connective tissue degradation.
在小鼠切牙萌出期间，牙周韧带的一部分会随着牙齿向咬合方向移动，并在牙龈中，即结合上皮的根尖处发生降解。当用电子显微镜观察时，一些结缔组织细胞（成纤维细胞）的细胞核和细胞质都出现了紊乱。在其他细胞中观察到含有部分降解的细胞成分的液泡。有时在这些液泡内观察到具有凝聚染色质外观的电子致密物质。基于这一观察结果，可以得出结论，异噬作用有助于成纤维细胞的分解过程。这些异噬细胞的超微结构与成纤维细胞相似。在成纤维细胞的细胞质液泡内观察到胶原纤维，这表明胶原被吞噬并可能在溶酶体中被消化。细胞间空间的一部分充满了中等电子密度的均匀物质，与一些胶原纤维混合在一起。在结合上皮的一些细胞内观察到部分降解的物质，这可能表明上皮有助于清除结缔组织降解的残余产物。
