Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
J Comp Neurol. 2011 Aug 15;519(12):2493-507. doi: 10.1002/cne.22637.
Owing to its ability to switch between free-living and parasitic modes of development, Parastrongyloides trichosuri represents a valuable model with which to study the evolution of parasitism among the nematodes, especially aspects pertaining to morphogenesis of infective third-stage larvae. In the free-living nematode Caenorhabditis elegans, developmental fates of third-stage larvae are determined in part by environmental cues received by chemosensory neurons in the amphidial sensillae. As a basis for comparative study, we have described the neuroanatomy of the amphidial sensillae of P. trichosuri. By using computational methods, we incorporated serial electron micrographs into a three-dimensional reconstruction of the amphidial neurons of this parasite. Each amphid is innervated by 13 neurons, and the dendritic processes of 10 of these extend nearly to the amphidial pore. Dendritic processes of two specialized neurons leave the amphidial channel and terminate within invaginations of the sheath cell. One of these is similar to the finger cell of C. elegans, terminating in digitiform projections. The other projects a single cilium into the sheath cell. The dendritic process of a third specialized neuron terminates within the tight junction of the amphid. Each amphidial neuron was traced from the tip of its dendrite(s) to its cell body in the lateral ganglion. Positions of these cell bodies approximate those of morphologically similar amphidial neurons in Caenorhabditis elegans, so the standard nomenclature for amphidial neurons in C. elegans was adopted. A map of cell bodies within the lateral ganglion of P. trichosuri was prepared to facilitate functional study of these neurons.
由于其在自由生活和寄生发育模式之间转换的能力，Parastrongyloides trichosuri 是一个很有价值的模型，可用于研究线虫寄生进化，尤其是与感染性第三期幼虫形态发生相关的方面。在自由生活的线虫秀丽隐杆线虫中，第三期幼虫的发育命运部分取决于化学感觉神经元在触角感器中接收到的环境线索。作为比较研究的基础，我们描述了 P. trichosuri 的触角感器的神经解剖结构。通过使用计算方法，我们将连续的电子显微镜照片整合到寄生虫触角神经元的三维重建中。每个触角由 13 个神经元支配，其中 10 个的树突过程几乎延伸到触角孔。两个特化神经元的树突过程离开触角通道，并终止于鞘细胞的内陷中。其中一个类似于秀丽隐杆线虫的指状细胞，终止于指状突起。另一个将单个纤毛投射到鞘细胞中。第三个特化神经元的树突过程终止于触角的紧密连接内。每个触角神经元都从其树突的末端追踪到其在侧神经节中的细胞体。这些细胞体的位置与秀丽隐杆线虫中形态相似的触角神经元的位置大致相同，因此采用了秀丽隐杆线虫触角神经元的标准命名法。编制了 P. trichosuri 侧神经节内细胞体的图谱，以方便对这些神经元进行功能研究。
