Jung Seo-Yoon, Green David William, Jung Han-Sung, Kim Eun-Jung
Division in Anatomy and Developmental Biology, Department of Oral Biology, Oral Science Research Center, BK21 PLUS Project, Yonsei University College of Dentistry, Seoul, South Korea.
Applied Oral Biosciences, Faculty of Dentistry, The University of Hong Kong, Hong Kong, Hong Kong, SAR.
Histochem Cell Biol. 2018 Jun;149(6):655-659. doi: 10.1007/s00418-018-1666-9. Epub 2018 Apr 12.
Enamel knot (EK) is known to be a central organ in tooth development, especially for cusp patterning. To trace the exact position and movement among the inner dental epithelium (IDE) and EK cells, and to monitor the relationship between the EK and cusp patterning, it is essential that we understand the cell cycle status of the EK in early stages of tooth development. In this study, thymidine analogous (IdU, BrdU) staining was used to evaluate the cell cycle phase of the primary EK at the early casp stage (E13.0) and the gerbil embryo (E19) in a developing mouse embryo. The centerpiece of this study was to describe the cell cycle phasing and sequencing during proliferation in the IDE according to the expression of IdU and BrdU following their injection at calculated time points. The interval time between IdU injection and BrdU injection was set at 4 h. As a result, the cell cycle in the IDE of the mouse and gerbil was found to be synchronous. Conversely, the cell cycle in primary EKs of mice was much longer than that of the IDE. Therefore, the difference of cell cycle of the IDE and the EK is related to the diversity of cusp patterning and would provide a new insight into tooth morphogenesis.
釉结（EK）是牙齿发育中的一个核心器官，尤其在牙尖形态形成方面。为了追踪内釉上皮（IDE）细胞和EK细胞的确切位置及运动，并监测EK与牙尖形态形成之间的关系，了解牙齿发育早期EK的细胞周期状态至关重要。在本研究中，使用胸腺嘧啶类似物（IdU、BrdU）染色来评估发育中小鼠胚胎早期尖牙阶段（E13.0）和沙鼠胚胎（E19）中初级EK的细胞周期阶段。本研究的核心是根据在计算时间点注射IdU和BrdU后的表达情况，描述IDE增殖过程中的细胞周期阶段划分和顺序。IdU注射与BrdU注射之间的间隔时间设定为4小时。结果发现，小鼠和沙鼠IDE中的细胞周期是同步的。相反，小鼠初级EK中的细胞周期比IDE中的长得多。因此，IDE和EK细胞周期的差异与牙尖形态的多样性有关，这将为牙齿形态发生提供新的见解。
