Ichikawa T, Tateda H
J Neurocytol. 1984 Apr;13(2):227-38. doi: 10.1007/BF01148117.
Profiles of the axonal endings of seven retinular cells (R1-7) from each of six stemmata (I-VI) of the butterfly Papilio xuthus were examined. Their axons enter the brain anteroventrally and project dorsally along the brain's lateral surface before entering the optic neuropil. Larval optic neuropil has two distinct areas, a (distal) lamina and a (proximal) medulla, connected by a chiasma. Intracellular administration of cobalt shows that distal retinular cells (R1-3 of stemmata I-IV, R1-3 and R6 of stemmata V and VI) terminate as short axons with plug or toothbrush-like endings in the lamina. Proximal retinular cells (R4-7 of stemmata I-IV, R4, R5 and R7 of stemmata V and VI) terminate as long axons in the chiasma or in the medulla. The long axons have fine branches in the lamina, chiasma and medulla. The two proximal cells (R5 and R7) are distinguished by their deeper endings and longer branches. The terminals of photoreceptors correspond to their photoreceptive properties and provide further evidence for the functional specialization of the photoreceptors.
对凤蝶六个单眼（I - VI）中每个单眼的七个视小网膜细胞（R1 - 7）的轴突末梢形态进行了检查。它们的轴突从前腹侧进入脑，在进入视神经节之前沿着脑的外侧表面向背侧投射。幼虫的视神经节有两个不同的区域，一个（远端的）外网层和一个（近端的）髓质，由一个交叉连接。细胞内注射钴显示，远端视小网膜细胞（单眼I - IV的R1 - 3，单眼V和VI的R1 - 3和R6）以短轴突终止于外网层，其末梢呈塞状或牙刷状。近端视小网膜细胞（单眼I - IV的R4 - 7，单眼V和VI的R4、R5和R7）以长轴突终止于交叉或髓质。长轴突在外网层、交叉和髓质中有细分支。两个近端细胞（R5和R7）的区别在于它们的末梢更深且分支更长。光感受器的末梢与其光感受特性相对应，并为光感受器的功能特化提供了进一步的证据。
