Weatherby T M, Lenz P H
Biological Electron Microscope Facility, Pacific Biomedical Research Center, University Hawaii at Manoa, 1993 East-West Road, Honolulu, HI 96822, USA.
Arthropod Struct Dev. 2000;29(4):275-88. doi: 10.1016/s1467-8039(01)00011-1.
The mechanoreceptors of the first antennae of Pleuromamma xiphias, a mesopelagic calanoid copepod, are critical for the detection of potential threats. These receptors exceed the physiological performance of other crustacean mechanoreceptors in sensitivity to water velocities as well as in frequency response. A study of these receptors was initiated to elucidate structure-function relationships. Morphologically, the receptors resemble the arthropod scolopidial organs by the presence of a scolopale tube. However, the rigidity of the copepod receptors greatly exceeds those described for crustaceans and other arthropods. The scolopale tube completely encloses the distal dendrites and it is firmly anchored to the cuticle. Microtubules are organized in register and arise from microtubule subfibers associated with crescent-shaped rods which extend from the basal body region to the setal socket. The distal dendrites are filled with a large number of cross-linked microtubules. Termination of the distal dendrites inside the lumen of the setae is gradual with a firm anchoring to the cuticle. A likely mechanism for mechanotransduction would involve a linkage between individual microtubules and mechano-gated channels in the dendritic membrane. The rigidity probably contributes to the high frequency sensitivity, and termination of the dendrite inside the seta increases the overall sensitivity of these receptors.
尖额平头水蚤（Pleuromamma xiphias）是一种中层桡足类哲水蚤，其第一触角的机械感受器对于检测潜在威胁至关重要。这些感受器在对水流速度的敏感度以及频率响应方面，超过了其他甲壳类动物的机械感受器的生理性能。为了阐明结构 - 功能关系，对这些感受器展开了一项研究。从形态学上看，这些感受器因存在一个围鞘管而类似于节肢动物的弦音器器官。然而，桡足类感受器的刚性大大超过了已描述的甲壳类动物和其他节肢动物的感受器。围鞘管完全包裹着远端树突，并牢固地锚定在角质层上。微管排列整齐，由与新月形杆相关的微管亚纤维产生，这些杆从基体区域延伸到刚毛窝。远端树突充满了大量交联的微管。远端树突在刚毛腔内的终止是逐渐的，并牢固地锚定在角质层上。一种可能的机械转导机制可能涉及单个微管与树突膜中的机械门控通道之间的联系。这种刚性可能有助于高频敏感度，并且树突在刚毛内的终止增加了这些感受器的整体敏感度。
