Bogéa Tami
Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut 06269-3043, USA.
Folia Parasitol (Praha). 2004 Dec;51(4):311-9.
Studies involving comparisons of taxa that vary in their degree of relatedness may allow the distinction of functional and phylogenetic components in cercarial sensory systems. In this study, cercariae of allocreadiids Bunodera Railliet, 1896 and Crepidostomum Braun, 1900, lecithodendriid Allassogonoporus Olivier, 1938 and opecoelid Allopodocotyle Pritchard, 1966 were compared as regards ultrastructure and chaetotaxy of sensory receptors as well as neuromorphology. Cercariae were treated with acetylthiocholine iodide and silver nitrate and some were processed for scanning and transmission electron microscopy. The types of cercarial sensory receptors differed in the presence of a tegumentary sheath, a dome-like base and a tegumentary collar, number of cilia (0, 1, 2 or more), cilium length (short, moderately long or long) and tegumentary collar length (low to moderately low, high or very high). Chaetotaxic patterns were consistent at the family level in all taxa studied. Irregular cholinergic nerve networks were identified. The present study indicates that the major categories of cercarial sensory receptors are nonciliated (including sheathed and subtegumentary types) and ciliated (including uncollared and collared types) receptors. It also allows the distinction of functional and phylogenetic components in the sensory systems of the cercariae studied. Functional components were reflected in the numbers of sensory receptors associated with each nerve region and in the ultrastructure and site-specificity of receptor types. Phylogenetic components included taxon-specific chaetotaxic patterns and receptor types.
涉及对亲缘关系程度不同的分类群进行比较的研究，可能有助于区分尾蚴感觉系统中的功能和系统发育成分。在本研究中，对1896年的Allocreadiidae科的Bunodera Railliet属、1900年的Crepidostomum Braun属、1938年的Lecithodendriidae科的Allassogonoporus Olivier属以及1966年的Opecoelidae科的Allopodocotyle属的尾蚴，就感觉受体的超微结构、刚毛排列以及神经形态学进行了比较。尾蚴用碘化乙酰硫代胆碱和硝酸银处理，部分尾蚴进行扫描和透射电子显微镜处理。尾蚴感觉受体的类型在是否存在皮层鞘、圆顶状基部和皮层领、纤毛数量（0、1、2或更多）、纤毛长度（短、中等长或长）以及皮层领长度（低至中等低、高或非常高）方面存在差异。在所研究的所有分类群中，刚毛排列模式在科级水平上是一致的。识别出了不规则的胆碱能神经网络。本研究表明，尾蚴感觉受体的主要类别是非纤毛受体（包括有鞘和皮层下类型）和纤毛受体（包括无领和有领类型）。它还能区分所研究尾蚴感觉系统中的功能和系统发育成分。功能成分反映在与每个神经区域相关的感觉受体数量以及受体类型的超微结构和位点特异性上。系统发育成分包括特定分类群的刚毛排列模式和受体类型。
