King D G, Wyman R J
J Neurocytol. 1980 Dec;9(6):753-70. doi: 10.1007/BF01205017.
Activity in the flight muscles and jump muscles in Drosophila can be stimulated by excitation of a pair of giant fibres that enter the thoracic ganglion from the brain. Contrary to previous descriptions, these giant fibres are not themselves motor axons. Each giant fibre contacts both a large motor axon and an interneuron. The motor axon innervates the ipsilateral tergotrochanteral (jump) muscle. The interneuron synapses in turn with the motor neurons that innervate the contralateral dorsal longitudinal flight muscle. The output synapses of this interneuron occur directly onto the motor axons within a peripheral nerve. The unusual peripheral location for these interneuron synapses suggests that the interneuron may function to speed up activation of the motor axons by bypassing integration within the motor neurons' dendritic trees. The synapses are typical dipteran chemical synapses, with occasional reciprocal contacts from the motor axons back onto the interneuron. The interneuron-motor axon synapses may be especially useful for morphological studies of identified synaptic contacts because their peripheral location makes them extremely easy to locate and identify.
果蝇飞行肌和跳跃肌的活动可通过一对从大脑进入胸神经节的巨纤维的兴奋来刺激。与之前的描述相反，这些巨纤维本身并非运动轴突。每条巨纤维都与一条大型运动轴突和一个中间神经元相连。运动轴突支配同侧的背板转子（跳跃）肌。中间神经元依次与支配对侧背纵飞行肌的运动神经元形成突触。该中间神经元的输出突触直接出现在外周神经内的运动轴突上。这些中间神经元突触在外周的不寻常位置表明，中间神经元可能通过绕过运动神经元树突内的整合来加速运动轴突的激活。这些突触是典型的双翅目化学突触，偶尔有运动轴突与中间神经元的反向接触。中间神经元 - 运动轴突突触对于已识别突触接触的形态学研究可能特别有用，因为它们在外周的位置使其极易定位和识别。
