Northcutt R G
J Comp Neurol. 1977 Aug 15;174(4):553-74. doi: 10.1002/cne.901740402.
Autoradiographic and silver methods indicate that the African and South American lungfishes, Protopterus and Lepidosiren, lack ipsilateral retinal projections. Contralaterally, the retina projects to the preoptic nucleus of the hypothalamus, to four discrete areas located in the lateral neuropil of the thalamus, to a superficial pretectal neuropil, to the upper half of the tectal neutropil, and to a laterally situated basal optic neuropil located in the rostral tegmentum. The overall pattern of the primary retinofugal projections is markedly similar to that of amphibians which suggests that lungfishes may be more closely related to amphibians than to actinopterygian fishes. Neotenic trends in both lepidosirenid lungfishes and urodeles may be expressions of parallelism, hence Latimeria and Neoceratodus must be examined to resolve this phylogenetic problem. A 300-fold range in the size of the eye, indicated by the number of ganglion cells present, occurs among lungfishes, salamanders and frogs. This variation may have implications for recognizing the morphological expression of selection operating on the visual systems of lepidosirenids and amphibians.
放射自显影法和银染法表明，非洲肺鱼和南美肺鱼（原鳍鱼属和美洲肺鱼属）缺乏同侧视网膜投射。在对侧，视网膜投射到下丘脑的视前核、丘脑外侧神经纤维网中的四个离散区域、一个浅的顶盖前神经纤维网、顶盖神经纤维网的上半部分以及位于吻侧被盖中的一个位于外侧的基底视神经神经纤维网。初级视网膜传出投射的总体模式与两栖动物的模式明显相似，这表明肺鱼与两栖动物的关系可能比与辐鳍鱼类的关系更密切。美洲肺鱼科肺鱼和有尾目动物中的幼态延续趋势可能是平行进化的表现，因此必须对矛尾鱼和澳洲肺鱼进行研究以解决这个系统发育问题。根据神经节细胞的数量显示，肺鱼、蝾螈和青蛙的眼睛大小有300倍的差异。这种差异可能对于识别作用于美洲肺鱼科和两栖动物视觉系统的选择的形态学表现具有启示意义。
