Harman A M, Coleman L A, Beazley L D
Department of Psychology, University of Western Australia, Nedlands.
Brain Behav Evol. 1990;36(1):30-8. doi: 10.1159/000115295.
We examined the mature retinal projections of the honey possum, Tarsipes rostratus, an Australian, diprotodont marsupial, using uni-ocular injections of horseradish peroxidase and tetramethylbenzidine processing. The suprachiasmatic nucleus, medial, lateral and dorsal terminal nuclei of the accessory optic tract, pretectal nuclei and superior colliculus received bilateral retinal input. Contralateral input only was observed in the lateral posterior nucleus. The pattern of input to these regions was essentially similar to that seen in other marsupials. Cyto-architectural examination of the dorsal lateral geniculate nucleus (dLGN) indicated that 5 laminae were present in the alpha-segment, but the beta-segment appeared to lack lamination. Input to the dLGN was bilateral, overlapping considerably, and was organised in a laminar fashion with 7 and 3 terminal bands in the alpha- and beta-segments, respectively. The monocular segment accounted for 12% of the total volume of the dLGN. In the alpha-segment, 2 terminal bands each received exclusively contralateral or ipsilateral input and 3 bilateral input. In the beta-segment, 2 terminal bands received bilateral and 1 contralateral input. The volumes of the nucleus receiving contralateral and ipsilateral input were 77 and 54% of the total, respectively. A marked overlap of input from the two eyes is an unusual feature for a diprotodont marsupial and has previously been seen only in the feathertail glider. Our findings for the dLGN are of interest in the light of recent serological and taxonomic studies which suggest a close link between the feathertail glider and the honey possum.
我们使用辣根过氧化物酶单眼注射和四甲基联苯胺处理方法，研究了澳大利亚双门齿有袋动物蜜袋鼯（Tarsipes rostratus）成熟的视网膜投射。视交叉上核、副视束的内侧、外侧和背侧终核、顶盖前核和上丘接受双侧视网膜输入。仅在外侧后核观察到对侧输入。这些区域的输入模式与其他有袋动物基本相似。对背外侧膝状核（dLGN）的细胞结构检查表明，α段有5层，但β段似乎缺乏分层。dLGN的输入是双侧的，有相当大的重叠，并以分层方式组织，α段和β段分别有7条和3条终末带。单眼段占dLGN总体积的12%。在α段，2条终末带分别仅接受对侧或同侧输入，3条接受双侧输入。在β段，2条终末带接受双侧输入，1条接受对侧输入。接受对侧和同侧输入的核体积分别占总体积的77%和54%。双眼输入的明显重叠是双门齿有袋动物的一个不寻常特征，以前仅在羽尾袋貂中见过。鉴于最近的血清学和分类学研究表明羽尾袋貂和蜜袋鼯之间有密切联系，我们对dLGN的研究结果很有意义。
