Tsuchiya Masahiro, Sasano Yasuyuki, Kagayama Manabu, Watanabe Makoto
Division of Aging and Geriatric Dentistry, Tohoku University Graduate School of Dentistry, Sendai, Japan.
Arch Histol Cytol. 2002 Jun;65(2):179-88. doi: 10.1679/aohc.65.179.
The question of whether odontoblast processes extend to the dentinal surface has been widely debated in previous studies. In this study odontoblast processes were investigated in the developing and aging dentin of rats and monkeys (Japanese macaques). For this purpose, F-actin of microfilaments and cellular membranes were stained with phalloidin and DiI, respectively. This dual staining demonstrated that positive signals for odontoblast processes were present in the dentinal surface in both the cusp and cervical regions of the dentin at 2 weeks of age. The tips of doubly positive processes were detectable in the dentinal surface in the cusp region even at 100 weeks of age, whereas in the cervical region they were retracted from the dentinal surface towards the pulp during the period of 3-6 weeks of age. During these stages, phalloidin-positive signals showing retracted odontoblast processes in the cervical region were closely associated with the interglobular dentin that was stained with sWGA-lectin. After 6 weeks of age, no association was observed between the processes and the interglobular dentin, since they were retracted approximately to the inner third portion of the dentinal tubules. This staining pattern can be detected until 100 weeks of age. Moreover, different distribution patterns of odontoblast processes between the two dentinal regions were also confirmed in dentin of monkey teeth. These results suggest that the existence of the regional differences in the extent of the odontoblast processes in the dentin, i.e., the persistence of the processes in the dentinal surface in the cusp region and their retraction from the dentinal surface in the cervical region.
成牙本质细胞突起是否延伸至牙本质表面的问题在以往研究中一直存在广泛争议。在本研究中，对大鼠和猴子（日本猕猴）发育中和老化的牙本质中的成牙本质细胞突起进行了研究。为此，分别用鬼笔环肽和DiI对微丝和细胞膜的F-肌动蛋白进行染色。这种双重染色表明，在2周龄时，牙本质尖部和颈部区域的牙本质表面均存在成牙本质细胞突起的阳性信号。即使在100周龄时，在牙尖区域的牙本质表面仍可检测到双阳性突起的尖端，而在颈部区域，它们在3 - 6周龄期间从牙本质表面向牙髓退缩。在这些阶段，显示颈部区域成牙本质细胞突起退缩的鬼笔环肽阳性信号与用sWGA-凝集素染色的球间牙本质密切相关。6周龄后，由于突起大约退缩到牙本质小管的内三分之一部分，因此未观察到突起与球间牙本质之间的关联。这种染色模式在100周龄之前均可检测到。此外，在猴牙的牙本质中也证实了两个牙本质区域之间成牙本质细胞突起的不同分布模式。这些结果表明，牙本质中成牙本质细胞突起范围存在区域差异，即牙尖区域牙本质表面突起持续存在，而颈部区域突起从牙本质表面退缩。
