Tadokoro O, Mishima H, Maeda T, Kozawa Y
Department of Anatomy, Nihon University School of Dentistry at Matsudo, Chiba, Japan.
Eur J Oral Sci. 1998 Jan;106 Suppl 1:519-23. doi: 10.1111/j.1600-0722.1998.tb02216.x.
The mode of development and structure of crocodilian teeth and periodontium parallels that of mammals, but the teeth are continuously replaced throughout the lifetime of those animals. In this report, the innervation and fibres of the crocodilian periodontal ligament were examined using histology, immunohistochemistry for S-100 protein and transmission electron microscopy. Crocodilian periodontal ligaments had the following characteristics: (1) horizontal fibres, which connect the alveolar bone to the root cementum and (2) longitudinal fibres, which ran parallel to the tooth axis, with nerves and blood vessels in the middle layer of the ligament. The apex of root and tooth germs were both embedded in thick circular fibres. S-100 protein was detected in neural elements including terminal portions which were densely distributed in the periodontal ligament and dental follicle. The S-100 positive neural elements formed a periodontal plexus. We found two types of nerve endings; free endings and simple encapsulated corpuscles as described in mammals. The presence of such nerve endings in caiman suggests that these teeth, in addition to having a biting function, may also act as highly sensitive sensory organs.
鳄鱼牙齿和牙周组织的发育模式及结构与哺乳动物相似，但这些动物在其一生中牙齿会不断替换。在本报告中，利用组织学、S-100蛋白免疫组织化学及透射电子显微镜对鳄鱼牙周韧带的神经支配和纤维进行了研究。鳄鱼牙周韧带具有以下特征：（1）连接牙槽骨与牙根牙骨质的水平纤维；（2）平行于牙轴走行的纵向纤维，神经和血管位于韧带的中间层。牙根尖和牙胚均嵌入厚的环形纤维中。在包括末端部分的神经成分中检测到S-100蛋白，这些末端部分密集分布于牙周韧带和牙囊。S-100阳性神经成分形成牙周丛。我们发现了两种神经末梢；如在哺乳动物中所描述的游离末梢和简单被囊小体。凯门鳄中存在此类神经末梢表明，这些牙齿除了具有咬的功能外，还可能充当高度敏感的感觉器官。
