Hokoç J N, Gawryszewski L G, Volchan E, Rocha-Miranda C E
Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro.
An Acad Bras Cienc. 1992 Sep;64(3):293-303.
The retinal distribution of ganglion cells with crossed and uncrossed projections in the South American opossum, Didelphis marsupialis, was revealed by delivering HRP to one optic tract or to retinal targets of one hemisphere. The cells with uncrossed projections are restricted to the temporal retina, comprising 1/3 of the total retinal area, with a sharp transition at the naso-temporal boundary. Besides being distributed over the nasal 2/3 of the retina, cells with crossed projections are intermingled with those with uncrossed projections over the entire temporal retina. Quantitative analysis about the representation of the horizontal meridian on four specimens revealed that the maximum density of cells with uncrossed projections is on the average located at 3.2 mm (SD = 0.21), i.e. 34.8 deg, temporal to the optic disk, falling to 10% at 2.1 mm (SD = 0.14) or 22.8 deg. On the other hand, the peak for cells with crossed projections is more nasally placed at 1.8 mm (SD = 0.18), i.e. 19.6 deg. Between these two maxima, the site wherein the densities of cells with crossed and uncrossed projections are about equal is on the average about 2.7 mm (SD = 0.25) form the optic disk, i.e. 29.3 deg. This estimate supports the hypothesis that the retinal intersection of the vertical meridian lies within the region of split representation of crossed and uncrossed ganglion cells. In addition, it was observed that the opossum's retina has a large contingent of cells with uncrossed projections temporal to an eccentricity of 2.7 mm from the optic disk, where it represents roughly 2/3 of the ganglion cells. These data corroborate the relevance of the opossum as a non-primate model for visual work.
通过将辣根过氧化物酶（HRP）注入南美负鼠（Didelphis marsupialis）的一条视束或一侧半球的视网膜靶点，揭示了具有交叉和不交叉投射的神经节细胞在视网膜上的分布情况。具有不交叉投射的细胞局限于颞侧视网膜，占视网膜总面积的1/3，在鼻颞边界处有明显的过渡。除了分布在视网膜的鼻侧2/3外，具有交叉投射的细胞在整个颞侧视网膜上与具有不交叉投射的细胞相互交织。对四个标本上水平子午线表征的定量分析表明，具有不交叉投射的细胞的最大密度平均位于视盘颞侧3.2毫米（标准差=0.21）处，即34.8度，在2.1毫米（标准差=0.14）或22.8度处降至10%。另一方面，具有交叉投射的细胞的峰值更偏向鼻侧，位于1.8毫米（标准差=0.18）处，即19.6度。在这两个最大值之间，具有交叉和不交叉投射的细胞密度大致相等的位置平均距视盘约2.7毫米（标准差=0.25），即29.3度。这一估计支持了这样一种假设，即垂直子午线的视网膜交叉点位于交叉和不交叉神经节细胞的分离表征区域内。此外，观察到负鼠的视网膜在距视盘偏心度为2.7毫米的颞侧有大量具有不交叉投射的细胞，约占神经节细胞的2/3。这些数据证实了负鼠作为视觉研究非灵长类模型的相关性。
