Saidel W M, Butler A B
Department of Zoology, University of Maryland, College Park.
Brain Behav Evol. 1991;38(2-3):154-68. doi: 10.1159/000114384.
Pantodon buchholzi, the freshwater butterfly fish, is a member of the Osteoglossomorpha, the most primitive of the four major teleost radiations. The projections of fibers originating in the dorsal and ventral hemiretinas in Pantodon, as determined with autoradiography, are reported here. Fibers originating in the ventral hemiretina reach their targets through the axial, medial and dorsal optic tracts. Fibers that originate in the dorsal hemiretina reach their points of termination by way of the axial, medial and ventral optic tracts. Projections of the various tracts to preoptic, thalamic, tubercular, pretectal and tectal regions, as described in the previous study of total retinal projections, were verified. The retinal projections to the preoptic, thalamic and tubercular nuclei do not map topographically. Ventral hemiretinal fibers are mapped, however, onto the dorsal part of the nucleus pretectalis superficialis pars parvocellularis, the rostral part of the dorsal accessory optic nucleus, the entire nucleus pretectalis periventricularis pars ventralis and the dorsomedial portion of the optic tectum. Ventral hemiretinal fibers also supply most if not all the retinal innervation to the central pretectal nucleus. In contrast, dorsal hemiretinal fibers are mapped onto the ventral part of nucleus pretectalis superficialis pars parvocellularis, the entire dorsal accessory optic nucleus and the ventrolateral portion of the optic tectum. The dorsal and ventral hemiretinal projections to the tectum about at a cytoarchitectonically recognizable point, indicating that no discontinuity is present in the retinal connectivity with the tectum. The pars parvocellularis of nucleus pretectalis superficialis is a simple, unfolded, and nonlaminar structure in Pantodon. This structure contrasts markedly with the more complex, folded structure of the nucleus in the majority of other examined teleosts. The orientation of the projections from the dorsal and ventral hemiretinas onto this nucleus in Pantodon is congruent with that seen in other fishes only after a schematic unfolding of the nucleus in these fishes.
淡水蝴蝶鱼（Pantodon buchholzi）是骨舌鱼目（Osteoglossomorpha）的一员，骨舌鱼目是硬骨鱼四大主要类群中最原始的一类。本文报道了通过放射自显影确定的淡水蝴蝶鱼背侧和腹侧半视网膜纤维的投射情况。起源于腹侧半视网膜的纤维通过轴向、内侧和背侧视束到达其靶点。起源于背侧半视网膜的纤维通过轴向、内侧和腹侧视束到达其终止点。正如之前关于视网膜整体投射的研究所描述的那样，各种视束向视前区、丘脑、结节、顶盖前区和顶盖区的投射得到了证实。视网膜向视前核、丘脑核和结节核的投射不存在拓扑映射。然而，腹侧半视网膜纤维映射到浅表顶盖前核小细胞部的背侧部分、背侧副视核的吻侧部分、整个室周顶盖前核腹侧部以及视顶盖的背内侧部分。腹侧半视网膜纤维也为中央顶盖前核提供了大部分（如果不是全部）视网膜神经支配。相比之下，背侧半视网膜纤维映射到浅表顶盖前核小细胞部的腹侧部分、整个背侧副视核以及视顶盖的腹外侧部分。背侧和腹侧半视网膜向顶盖的投射在一个细胞构筑上可识别的点处相交，这表明视网膜与顶盖之间的连接不存在间断。在淡水蝴蝶鱼中，浅表顶盖前核的小细胞部是一个简单、未折叠且无分层的结构。这种结构与大多数其他已研究硬骨鱼中该核更复杂的折叠结构形成了显著对比。在淡水蝴蝶鱼中，背侧和腹侧半视网膜向该核的投射方向，只有在对其他鱼类的该核进行示意性展开后，才与在其他鱼类中看到的方向一致。
