Kindaichi K
Arch Histol Jpn. 1980 Oct;43(4):289-304. doi: 10.1679/aohc1950.43.289.
Cell death in the epithelial tooth germs of mouse mandibular molars from the 12th to the 14th day of gestation was investigated by electron and light microscopy. Light microscopy revealed granular substances in the epithelial portion of the tooth germ on the 12th day, and an increase in their number to the 14th day when the enamel knot developed. In the areas where granular substances were observed by the light microscope, electron microscopy revealed cells with condensed chromatin. The cytoplasm of these cells increased in electron density, the cisterns of rough endoplasmic reticulum were dilated and the cristae of mitochondria disappeared. These cells were comparable to the physiologically degenerative cells reported in other organs. These degenerative cells are joined to adjacent cells by desmosomes and are believed to be derived from the epithelial cells. Further, degenerative bodies, composed of amorphous structures and enveloped by a limiting membrane, were observed in the epithelial cells. They are presumed to be derived from the degenerated cells engulfed by neighboring cells. From this evidence, phagocytic ability is attributed to the epithelial cells of the tooth germ.
通过电子显微镜和光学显微镜研究了妊娠第12天至第14天小鼠下颌磨牙上皮牙胚中的细胞死亡情况。光学显微镜显示，在第12天牙胚的上皮部分有颗粒物质，到第14天釉结形成时其数量增加。在光学显微镜观察到颗粒物质的区域，电子显微镜显示染色质浓缩的细胞。这些细胞的细胞质电子密度增加，粗面内质网池扩张，线粒体嵴消失。这些细胞与其他器官中报道的生理性退化细胞相似。这些退化细胞通过桥粒与相邻细胞相连，据信来源于上皮细胞。此外，在上皮细胞中观察到由无定形结构组成并被限制膜包裹的退化小体。推测它们来源于被相邻细胞吞噬的退化细胞。根据这些证据，吞噬能力归因于牙胚的上皮细胞。
