【摘要】 采用树脂石腊 (Colophony paraffin ,CP)组织包埋切片技术和链霉菌抗生物素蛋白 -过氧化酶 (Strep tavidin peroxidase ,SP)免疫组织化学方法 ,研究了 5 HT能神经元在日本弓背蚁 (Camponotusjaponicus)视叶中的分布。 5 HT阳性纤维起源于少量的细胞体 ,但在其视叶不同纤维网中有广泛的分布 ,呈现明显的静脉曲张状。染色强度在 3个视觉纤维网各不相同 ,并出现分层现象。结果表明 5 HT是在大面积神经丛区域 ,而不是在局部神经丛区域起作用更多还原

【Abstract】 Camponotus japonicus (Formicidae, Hymenoptera) is a typical social ins ect. Because of its comparatively concentrated and concise nervous system it is a good experimental model for the study of visual information processing in comp ound eyes and the structure and function of the insect brain and nervous system. Optic lobes are the visual center in insect compound eyes and the anatomical st ructure and electrophysiological characteristics of these organs have been studi ed in detail. The distribution of 5 HT immunoreactive neurons and their pathway s has been reported in some insects. However, the distribution of 5 HT in the op t ic lobes and brain of Campontus japonicus has not yet been investigated. C P (Col ophony paraffin) embedding tissue section technique and immunohistochemical st re ptalidin peroxidase (SP) methods were employed to slice and stain Campontus j apo nicus optic lobes. By investigating 5 HT immunoreactivity, the distribution of 5 HT in the optic lobes of Campontus japonicus can be determined, which can provi de information useful for the further study of insect brain neurobiology. 5 HT like immunoreactive processes originate from a relatively small number of cell bodies but each neuron has layers of processes over a large volume of the neur opil of the optic lobe. All neuropil regions of the optic lobe, the lamina, medu lla and lobula, contain 5 HT immunoreactive varicose fibers, which were distinc t in morphology and degree of staining. These all showed pronounced stratificatio n. The lamina is divided into layers A, B and C. Staining indicated that 5 HT i mmunoreactivity in layer A and B was weaker while that in C was stronger and we ll distributed (Plate Ⅰ: 1). These 5 HT varico se fibers were arranged in a columnar form and the columns were interconnected b y laterally projecting fibers. Medulla could be divided into nine layers accordi ng to the degree of staining. The staining of the first, second, third, seventh, eighth and ninth layers on both sides was lighter and immunoreactivity was weak er. 5 HT immunoreactive fibers in the fourth, fifth and sixth layers, which wer e vertical to the columnar cells of the medulla, was distributed extensively and stained even in the middle of the medulla, forming a characteristic centripetal mesh pattern (Plate Ⅰ: 3). Lobula could be divided into five layers for 5 HT im munoreactive fibers (PlateⅠ:5). The staining of the second layer was the lighte st, while the first and fourth layers lacked any immunoreactive fibers. The thir d and fifth layers were very thin with dark and clear 5 HT immunoreactive fiber s . These two centripetally orientated layers were vertical to the positive fiber layer of the medulla. A few diffused fibers were revealed in the fifth layer. Th ere were two groups of large immunoreactive neurons in the mid posterior parts o f protocerebrum. Their axons ran in bundles, some thin branches of which invaded a large area of the protocerebrum. Some of them also invaded the lobula and med ulla (PlateⅠ: 6). In addition, we could see 3 clear and weak immunoreactive vis ual fiber tracts: medulla lateral protocerebrum fiber tract (Plate Ⅰ: 7), lobu l a lateral protocerebrum fiber tract (PlateⅠ:8) and lobula lobula fiber tract. 5 HT immunoreactivity was obvious in outer chiasma (PlateⅠ: 2) but was weak in th e inner chiasma. There were three kinds of neurons related to optic lobes: amacr ine cells, columnar neurons and tangential neurons. The number of 5 HT immunore a ctive neurons was about 20, which were located on both sides of the inner chiasm a, between the lamina and medulla, medulla and lobula, lobula and protocerebrum (Plate Ⅰ: 4). From the distribution of 5 HT immunoreactive neurons, we infer t ha t 5 HT is more important in mediating distant rather than local neural interact i ons. Furthermore, 5 HT immunoreactivity in the lamina of optic lobes was strong , which might be related to the underground living habit and an adaptation to the consequent marked variation in light intensity .更多还原