Abstract 【Aim】 This study aims to investigate the anatomy of the optic lobes of adults of the oriental armyworm, Mythimna separata (Lepidotpera: Noctuidae) and the distribution of 5-hydroxytryptamine (5-HT) in the neuroplis of the optic lobes. 【Methods】 The tissue embedding and section, immunohistochemical staining with synaptic protein antibody and anti-5-HT serum were used to label the neuropil structure of the optic lobe and 5-HT in M. separata adults, respectively. The digital images of the optic lobes were obtained by using laser scanning confocal microscopy. The identification of neuropils and the grouping and counting of 5-HT immunoreactive (5-HTi) cell bodies were performed using image software. 【Results】 The optic lobe of M. separata adults is composed of five neuropils, i.e., lamina, medulla, accessory medulla, lobula, and lobula plate. There are about 40 5-HTi cell bodies in each optic lobe, and all the five neuropil regions contain 5-HTi neural processes. 5-HTi neural processes in lamina are originated from the tangential neurons of the optic lobe, and the processes of medulla are from the tangential neurons, centrifugal neurons and amacrine neurons. Medulla is distributed into mainly three layers, in which the middle layer possesses the densest 5-HTi processes. A few of 5-HTi processes exist in accessory medulla. In the lobula and lobula plate, the 5-HTi processes are originated from the centrifugal neurons. At least two layers of 5-HTi processes in lobula and lobula plate were observed. A few of neural processes project to medulla and connect lobula, lobula plate and medula. 【Conclusion】 5-HT immunoreactive fibers are widely distributed in the optic lobe of M. separata. The results provide the basic knowledge of neural anatomy for further studying the role of 5-HT in the visual system of M. separata.
GUO Pei,MA Bai-Wei,ZHAO Xin-Cheng et al. Distribution of 5-hydroxytryptamine in the optic lobes of the oriental armyworm, Mythimna separata (Lepidotpera: Noctuidae)[J]. ACTA ENTOMOLOGICA SINICA, 2018, 61(6): 668-675.