Watson A H, Burrows M
J Comp Neurol. 1985 Oct 15;240(3):219-32. doi: 10.1002/cne.902400302.
Spiking local interneurones in the metathoracic ganglion of the locust have two fields of neuropilar branches linked by a single process. One, with numerous fine neurites of relatively uniform diameter, is in a ventral area of neuropile where the afferents from hairs on a hind leg also terminate. The other, with sparser and varicose neurites, is in a more dorsal area of neuropile where the motor neurones of the leg muscles have many neurites. Physiological studies have shown that these interneurones receive direct inputs from some hair afferents and in turn synapse directly upon some leg motor neurones (Burrows and Siegler, '82; Siegler and Burrows, '83). The distribution of synapses in these two fields was revealed by injecting HRP intracellularly into an interneurone following its physiological characterization. In the ventral field, the majority of synapses are input synapses. Many are from profiles with round agranular vesicles of similar diameter to those of known afferents. Other presynaptic profiles contain pleomorphic agranular, or large round granular, vesicles. There are also some output synapses, each with only a small population of vesicles. Most input synapses are made onto small-diameter neurites, whereas the majority of outputs are made from the larger-diameter neurites. In the dorsal field, the majority of synapses are output synapses. They are made from vesicle-filled varicosities onto postsynaptic profiles of small diameter. A single varicosity can be the site of many output synapses. Input synapses are few in number, but occur close to the output synapses. The absence of varicosities in the ventral field cannot therefore be correlated with a lack of output synapses and while the dorsal varicosities can be the sites of output, they can also receive input synapses.
蝗虫后胸神经节中的爆发性局部中间神经元有两个神经毡分支区域，由单个突起相连。一个区域有许多直径相对均匀的细神经突，位于神经毡的腹侧区域，后足毛发的传入神经也在此终止。另一个区域的神经突较稀疏且有膨体，位于神经毡更靠背侧的区域，腿部肌肉的运动神经元在此有许多神经突。生理学研究表明，这些中间神经元从一些毛发传入神经接收直接输入，并依次直接与一些腿部运动神经元形成突触（伯罗斯和西格勒，1982年；西格勒和伯罗斯，1983年）。在对中间神经元进行生理学特征鉴定后，通过向其细胞内注射辣根过氧化物酶（HRP），揭示了这两个区域突触的分布情况。在腹侧区域，大多数突触是输入突触。许多来自具有圆形无颗粒小泡的突触小体，其直径与已知传入神经的小泡直径相似。其他突触前突触小体含有多形性无颗粒或大的圆形有颗粒小泡。也有一些输出突触，每个输出突触只有少量小泡。大多数输入突触形成于小直径神经突上，而大多数输出突触则由较大直径的神经突发出。在背侧区域，大多数突触是输出突触。它们由充满小泡的膨体与小直径的突触后突触小体形成。单个膨体可以是许多输出突触的位点。输入突触数量很少，但靠近输出突触。因此，腹侧区域没有膨体与缺乏输出突触并无关联，而背侧膨体虽然可以是输出位点，但也可以接收输入突触。
