Vaglia Janet L, White Kurt, Case Alison
DePauw University, Department of Biology, 1 E Hanna Street, Greencastle Indiana 46135.
Acta Zool. 2012 Jan;93(1):2-13. doi: 10.1111/j.1463-6395.2010.00475.x.
Typically the number of vertebrae an organism will have post-embryonically is determined during embryogenesis via the development of paired somites. Our research investigates the phenomenon of vertebral addition in salamander tails. We describe body and tail growth, and patterns of postsacral vertebral addition and elongation in context with caudal morphology for four plethodontids (), and one ambystomatid. and have paedomorphic life cycles; , and are biphasic. Specimens were collected, borrowed and/or purchased, and cleared and stained for bone and cartilage. Data collected include snout-vent length (SVL), tail length (TL), vertebral counts and centrum lengths. species with biphasic life cycles had TLs that surpassed SVL following metamorphosis. Tails in paedomorphic species elongated but rarely exceeded body length. Larger TLs were associated with more vertebrae and longer vertebrae in all species. We observed that rates of postsacral vertebral addition varied little amongst species. Regional variation along the tail becomes prominent following metamorphosis in biphasic developers. In all species vertebrae in the posterior one-half of the tail taper towards the tip. We suggest a developmental link might exist between the ability to continually add vertebrae and regeneration in salamanders.
通常，生物体胚胎发育后的椎骨数量是在胚胎发生过程中通过成对体节的发育来确定的。我们的研究调查了蝾螈尾巴中椎骨增加的现象。我们描述了四种无肺螈科动物和一种钝口螈科动物的身体和尾巴生长情况，以及骶后椎骨增加和伸长的模式与尾形态的关系。 和 具有幼态持续的生命周期； 、 和 是双相的。标本通过采集、借用和/或购买获得，并进行骨骼和软骨的透明和染色处理。收集的数据包括吻肛长度（SVL）、尾巴长度（TL）、椎骨计数和椎体长度。具有双相生命周期的 物种在变态后尾巴长度超过了吻肛长度。幼态持续物种的尾巴会伸长，但很少超过身体长度。在所有物种中，较大的尾巴长度与更多的椎骨和更长的椎骨相关。我们观察到，骶后椎骨增加的速率在不同物种之间变化不大。在双相发育的物种中，变态后尾巴上的区域差异变得明显。在所有物种中，尾巴后半部分的椎骨向尾尖逐渐变细。我们认为，蝾螈持续增加椎骨的能力与再生之间可能存在发育上的联系。
