版纳鱼螈牙齿的形态及发育

Tooth Morphology and Development of Ichthyophis bannanicus

对我国特有的濒危珍稀两栖动物版纳鱼螈(Ichthyophis bannanicus)牙齿的形态及其发育进行了研究。结果表明,版纳鱼螈牙齿发生于口腔上皮的底层细胞。一颗完整的牙齿由齿冠、纤维环和肉茎三部分构成,为同型钉状双尖齿。牙齿在上、下颌均排列成两排,每个齿位着生1～2颗牙齿。齿位数和齿数通常上颌齿多于下颌齿,上颌舌侧齿多于唇侧齿,下颌唇侧齿多于舌侧齿。随着个体的生长发育,齿位数和齿数会在颌后部增加。亚成体和成体有大量换齿或脱齿现象。牙齿从着生稀疏、功能齿和替换齿夹杂着生趋向功能齿密集整齐着生。同时,将此研究结果与其他蚓螈类进行了比较和分析。

The Yunnan Caecilian （Ichthyophis bannanicus） is the Gymnophiona species found only in China. Here we report the dentition of I. bannanicus at different developmental stages. The results show that the teeth of I. bannanicus are derived from the basal layer cells of the oral epidermis. A mature tooth has two parts linked by a fibrous ring, namely pedicel and crown. The teeth are homodont and nail-like with bicuspid. Both maxilla and submaxilla of the adult individuals have two teeth rows, and one or two teeth grow from each locus. But the numbers of teeth and loci in the maxilla are usual more than those in the submaxilla. Moreover, the number of lingual series teeth is more than that of labial series teeth in the maxilla, while opposite trend is observed in the submaxilla. The number and loci of teeth increase at the posterior jaw as individual grows. Numerous teeth are found in the state of replacement or abscission in the sub-aduh and adult. Meanwhile, sparse attachment of the functional teeth interlaced with unfunetional teeth change to dense and regular attachment of functional teeth. We also compare the dentition of 1. bannanicus with that of other caecilians.