Kawasaki F, Kita H
Department of Physiology, Kawasaki Medical School, Okayama, Japan.
J Comp Neurol. 1995 Jan 30;352(1):134-46. doi: 10.1002/cne.903520110.
Detailed morphological and physiological studies on the insect abdominal muscles, including their innervation and neuromuscular transmission, are essential for understanding their important role in respiratory movements. There are both longitudinal and transverse muscles in the ventral abdominal segments of the cricket, Gryllus bimaculatus. Muscle 202 was selected as an example of a longitudinal muscle. This muscle is, on average, 1.4 mm long, paired on both sides of the abdomen, and consists of 127 fibers whose mean maximum diameter is 32 microns; the average sarcomere length is 8.1 microns. It is innervated by two ipsilateral motoneurons in the second abdominal ganglion, the axons of which run in the ipsilateral first nerve root of the third abdominal ganglion. Two motor axons run in parallel from the two cell bodies and innervate in close proximity. Accordingly, large and small excitatory junctional potentials (EJPs) are recorded from the same fiber with slightly different thresholds when the first nerve root of the third abdominal ganglion is stimulated. Muscle 203, which is a transverse muscle that extends across the fifth abdominal sternum and is located over the fourth abdominal ganglion and muscle 202 on both sides, is, on average, 2.9 mm long and consists of 86 fibers with a maximum diameter of 33 microns. The average sarcomere length is 7.9 microns. The right or left half of the muscle is innervated mainly by a contralateral motoneuron in the third abdominal ganglion through the ipsilateral first nerve root of the third abdominal ganglion. Nerve branches of the first nerve root also reach muscles 188 and 218. Muscle 203 is additionally innervated by the first nerve roots of abdominal ganglia 1, 2, and 4. These innervations were ascertained both electrophysiologically and histologically. Individual muscle fibers of muscle 203 produced small EJPs in response to stimulation of the first nerve roots of abdominal ganglia 2, 3, and 4 and large EJPs in response to stimulation of the root from the first abdominal ganglion. The large and small EJPs in muscle 203 have properties similar to those in muscle 202.
对昆虫腹部肌肉进行详细的形态学和生理学研究，包括其神经支配和神经肌肉传递，对于理解它们在呼吸运动中的重要作用至关重要。双斑蟋（Gryllus bimaculatus）腹部腹节既有纵向肌肉也有横向肌肉。选取肌肉202作为纵向肌肉的一个例子。这块肌肉平均长1.4毫米，在腹部两侧成对存在，由127根纤维组成，其平均最大直径为32微米；平均肌节长度为8.1微米。它由第二腹神经节中的两个同侧运动神经元支配，其轴突在第三腹神经节的同侧第一神经根中运行。两条运动轴突从两个细胞体平行延伸并在附近支配。因此，当刺激第三腹神经节的第一神经根时，在同一根纤维上会记录到阈值略有不同的大、小兴奋性接头电位（EJP）。肌肉203是一块横向肌肉，横跨第五腹节腹板，位于第四腹神经节以及两侧的肌肉202上方，平均长2.9毫米，由86根最大直径为33微米的纤维组成。平均肌节长度为7.9微米。该肌肉的右半部分或左半部分主要由第三腹神经节中的一个对侧运动神经元通过第三腹神经节的同侧第一神经根支配。第一神经根的神经分支也延伸至肌肉188和218。肌肉203还由第一、第二和第四腹神经节的第一神经根额外支配。这些神经支配通过电生理学和组织学方法得以确定。肌肉203的单个肌纤维在受到第二、第三和第四腹神经节第一神经根刺激时产生小的EJP，而在受到第一腹神经节神经根刺激时产生大的EJP。肌肉203中的大、小EJP具有与肌肉202中类似的特性。
