Dentition and dentigerous bones in juveniles and adults of Polypterus senegalus (Cladistia, Actinopterygii)
Dentition and dentigerous bones in juveniles and adults of Polypterus senegalus (Cladistia, Actinopterygii)
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DOI：
10.1016/s0940-9602(98)80076-9
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发表时间：
1998-06-01
影响因子：
2.2
通讯作者：
Wacker, K
中科院分区：
文献类型：
--
作者：
Clemen, G;Bartsch, P;Wacker, K
利用扫描电镜技术对塞内加尔多鳍鱼幼鱼和成鱼的牙齿类型、排列方式和牙齿替换方式进行了研究。除了角骨外，口咽部的所有真皮骨几乎完全被牙齿覆盖。鳃器也是如此，只有舌骨骨骼没有牙齿。牙齿是统一的单尖牙和圆锥形，但可以根据形状和大小分为三种类型。这些类型和牙齿替换的模式是每个真皮骨的特征。在某些颌骨中，每颗牙齿都有一颗位于舌侧的替换牙齿。前上颌骨、上颌骨和齿骨的牙齿排列成一条线，皮腭骨、冠状骨和犁骨的牙齿排列成几条线，大小也有不同。所有其他含牙元素的替代牙齿在现有牙髓开口的顶部发育，只有在前一颗牙齿吸收后才形成一个封闭的共同牙髓复合体。鳃器真皮骨的齿板通过韧带联合仅与软骨膜骨化和鳃弓元件的软骨或结缔组织材料相连。在齿系及其与头部的骨头在Polypterus seneelus熊的相似性，以先进的放线菌的一方面（如分化的牙齿类型，安排），但也有一些相似性生活两栖类（锚定材料和更换模式）的另一方面。颌骨的外齿弓和内齿弓中的大牙齿的单一边缘线的突出是多鳍鱼的一个特点，在某种程度上与放射鳍鱼和四足动物中类似的单线性牙齿排列的衍生状态相似。
Tooth types, their arrangement and the mode of tooth replacement were studied in juvenile and adult specimens of Polypterus senegalus by means of scanning electron microscopy of cleared and stained specimens as well as sections. All the dermal bones of the oropharynx are almost completely covered with teeth except for the angulare. The same is true for the branchial apparatus where only the hyoid skeleton is toothless. The teeth are uniformly monocuspid and conical, but can be classified according to shape and size into three types. These types and the mode of tooth replacement are characteristic for each dermal bone. In some of the jaw bones each tooth possesses a lingually situated replacement tooth. This is true for the teeth of the premaxillary, the maxillary, and the dentary which are arranged in a single line, and those of the dermopalatine, the coronoids, and the vomer which are in several lines and graded in size. Replacement teeth of all the other dentigerous elements develop on top of existing pulpal openings, forming an anastomosing common pulpal complex only after resorption of the previous tooth. The tooth plates of the dermal bones of the branchial apparatus are connected by syndesmosis only to the perichondrally ossified and to the cartilaginous or connective tissue material of the elements of the gill-arches. The dentition and its association with the bones of the head in Polypterus senegalus bear resemblances to advanced actinopterygians on the one hand (e.g. differentiation of tooth-types, arrangement), but also some similarities to living Amphibia (anchoring material and mode of replacement) on the other. The accentuation of a single marginal line of large teeth in both, the outer and the inner dental arcade of the jaws is a peculiarity of Polypterus that in a way parallels the derived state of similar mono-linear tooth arrangements in Actinopterygii and Tetrapoda.