Presson J, Fernald R D, Max M
J Comp Neurol. 1985 May 15;235(3):360-74. doi: 10.1002/cne.902350307.
The organization of retinofugal projections was studied in a cichlid fish by labelling small groups of retinal ganglion cell axons with either horseradish peroxidase or cobaltous lysine. Two major findings resulted from these experiments. First, optic tract axons show a greater degree of pathway diversity than was previously appreciated, and this pathway diversity is related to the target nuclei of groups of axons. The most striking example is the formation of the medial optic tract. Fibers that will become the medial optic tract move abruptly away from their neighbors, at about the level of the optic chiasm, and coalesce at the dorsomedial edge of the marginal optic tract. The medial optic tract projects to the thalamus, the dorsal pretectum, and the deep layer of the optic tectum. The axial optic tract is a group of fibers which segregates from the most medial portion of the marginal optic tract, at about the level of the optic chiasm. The axial tract stays medial to the marginal optic tract for a few hundred microns and then curves laterally to rejoin the marginal optic tract. At least some axial trat axons terminate in the suprachiasmatic nucleus. Within the marginal optic tract, retinal ganglion cell axons from a given retinal quadrant are always segregated into at least two groups. The smaller group projects to the superficial pretectal nucleus. The larger group projects to the superficial layer of the optic tectum. Second, each nontectal retinal termination site receives a unique pattern of retinal input. Within the pretectum the parvocellular superficial pretectal nucleus receives a highly retinotopically organized input from all retinal regions; the basal optic nucleus receives a roughly retinotopically organized input from all retinal regions; the dorsal pretectum receives an input from all retinal regions; and the central pretectal nucleus receives input only from the ventral hemiretina. Within the diencephalon the thalamus receives an input from all retinal regions, but this input is not retinotopically organized; the suprachiasmatic nucleus receives input from the region of central retina that lies just dorsal to the optic nerve head, via the axial optic tract. The accessory optic nucleus receives input from the dorsal hemiretina.
通过用辣根过氧化物酶或赖氨酸钴标记少量视网膜神经节细胞轴突，对一种丽鱼科鱼类的视网膜传出投射组织进行了研究。这些实验得出了两个主要发现。首先，视束轴突显示出比以前认识到的更大程度的通路多样性，并且这种通路多样性与轴突群的靶核有关。最显著的例子是内侧视束的形成。将成为内侧视束的纤维在视交叉水平左右突然与其相邻纤维分开，并在边缘视束的背内侧边缘合并。内侧视束投射到丘脑、背侧顶盖前区和视顶盖深层。轴性视束是一组在视交叉水平左右从边缘视束最内侧部分分离出来的纤维。轴性视束在边缘视束内侧保持几百微米，然后向外侧弯曲重新与边缘视束汇合。至少一些轴性视束轴突终止于视交叉上核。在边缘视束内，来自给定视网膜象限的视网膜神经节细胞轴突总是至少被分为两组。较小的一组投射到顶盖前浅层核。较大的一组投射到视顶盖浅层。其次，每个非顶盖视网膜终末部位都接受独特的视网膜输入模式。在顶盖前区内，小细胞顶盖前浅层核接受来自所有视网膜区域的高度视网膜拓扑组织化输入；基底视核接受来自所有视网膜区域的大致视网膜拓扑组织化输入；背侧顶盖前区接受来自所有视网膜区域的输入；而顶盖前中央核仅接受来自腹侧半视网膜的输入。在间脑内，丘脑接受来自所有视网膜区域的输入，但这种输入不是视网膜拓扑组织化的；视交叉上核通过轴性视束接受来自紧邻视神经乳头背侧的中央视网膜区域的输入。副视核接受来自背侧半视网膜的输入。
