Meier T, Reichert H
Department of Zoology, University of Geneva, Switzerland.
J Neurobiol. 1990 Jun;21(4):592-610. doi: 10.1002/neu.480210407.
Two different types of ears characterize the order of Orthopteran insects. The auditory organs of grasshoppers and locusts (Caelifera) are located in the first abdominal segment, those of bushcrickets and crickets (Ensifera) are found in the tibiae of the prothoracic legs. Using neuron-specific antibody labelling, we describe the ontogenetic origin of these two types of auditory organs, use comparative developmental studies to identify their segmental homologs, and on the basis of homology postulate their evolutionary origin. In grasshoppers the auditory receptors develop by epithelial invagination of the body wall ectoderm in the first abdominal segment. Subsequently, at least a part of the receptor cells undergo active migration and project their out-growing axons onto the next anterior intersegmental nerve. During this time the receptor cells and their axons express the cell-cell adhesion molecule, Fasciclin I. Similar cellular and molecular differentiation processes in neighboring segments give rise to serially homologous sensory organs, the pleural chordotonal organs in the pregenital abdominal segments, and the wing-hinge chordotonal organs in the thoracic segments. In more primitive earless grasshoppers pleural chordotonal organs are found in place of auditory organs in the first abdominal segment. In bushcrickets the auditory receptors develop in association with the prothoracic subgenual organ from a common developmental precursor. The auditory receptor neurons in these insects are homologous to identified mechanoreceptors in the meso- and metathoracic legs. The established intra- and interspecies homologies provide insight into the evolution of the auditory organs of Orthopterans.
直翅目昆虫的一个特征是有两种不同类型的耳朵。蚱蜢和蝗虫（蝗亚目）的听觉器官位于腹部第一节，螽斯和蟋蟀（螽亚目）的听觉器官则位于前胸腿的胫节。我们利用神经元特异性抗体标记来描述这两种听觉器官的个体发生起源，通过比较发育研究来确定它们的体节同源物，并基于同源性推测它们的进化起源。在蚱蜢中，听觉感受器通过腹部第一节体壁外胚层的上皮内陷发育而成。随后，至少一部分感受器细胞进行主动迁移，并将其生长中的轴突投射到下一个前节间神经上。在此期间，感受器细胞及其轴突表达细胞间粘附分子Fasciclin I。相邻体节中类似的细胞和分子分化过程产生了一系列同源的感觉器官，即生殖前腹部体节中的胸膜弦音器官和胸部体节中的翅铰链弦音器官。在更原始的无耳蚱蜢中，胸膜弦音器官取代了腹部第一节中的听觉器官。在螽斯中，听觉感受器与前胸膝下器官由一个共同的发育前体发育而来。这些昆虫中的听觉感受器神经元与中胸和后胸腿中已确定的机械感受器同源。已确定的种内和种间同源性为直翅目昆虫听觉器官的进化提供了见解。
