Kirby M A, Steineke T C
Department of Pediatrics, School of Medicine, Loma Linda University, CA 92350.
Vis Neurosci. 1991 Dec;7(6):513-30. doi: 10.1017/s0952523800010324.
The pattern of dendritic stratification of retinal ganglion cells in the fetal monkey (Macaca mulatta) was examined using horseradish peroxidase and retinal explants. Ganglion cells in the rhesus monkey are born between embryonic day (E) 30-70 (LaVail et al., 1983). At E60, E67, and E68, approximately 50% of all ganglion cells within the central 3.0 mm of the retina had dendritic arbors that were unistratified within the inner plexiform layer (IPL), while the remaining 50% had bistratified arbors. Unistratified cells had relatively flat arbors that ramified within a restricted portion of the IPL. In contrast, bistratified cells had one portion of the arbor that branched in the inner half of the IPL and a second portion that branched in the outer half of the IPL. Relatively few bistratified cells were encountered in the central 1.0 mm of the retina but were more numerous with increasing eccentricity. At E81, E90, and E110, the dendritic arbors of ganglion cells increased in both area and complexity, but occupied a relatively small percentage of the total depth of the IPL. The bistratified cells encountered at these fetal ages were typically located in the far retinal periphery. Between E125-E140, the dendritic arbors of individual ganglion cells increased in area and depth to occupy a greater proportion of the total IPL than at earlier fetal ages. These observations suggest that ganglion cells in the macaque undergo at least three stages of dendritic stratification: (1) an initial period of dendritic growth during which the cells have either unistratified or bistratified dendritic arbors; (2) a loss of the majority of bistratified cells through cell death or remodeling of the arbor; and (3) growth or expansion of the arbor to occupy a greater percentage of the total depth of the IPL. The first two stages are similar to recent observations in the fetal cat (Maslim & Stone, 1988) with the exception that dendritic development in the primate lacks an initial diffuse ingrowth to the IPL. Additionally, primate ganglion cells undergo a third stage of dendritic growth in late fetal development during which the arbor occupies a greater proportion of the depth of the IPL.
利用辣根过氧化物酶和视网膜外植体，研究了胎猴（猕猴）视网膜神经节细胞的树突分层模式。恒河猴的神经节细胞在胚胎期第（E）30 - 70天之间生成（LaVail等人，1983）。在E60、E67和E68时，视网膜中央3.0毫米范围内约50%的神经节细胞具有在内网状层（IPL）内单分层的树突分支，而其余50%具有双分层分支。单分层细胞具有相对扁平的分支，在IPL的受限部分内分支。相比之下，双分层细胞的一部分分支在IPL的内半部分，另一部分分支在IPL的外半部分。在视网膜中央1.0毫米范围内遇到的双分层细胞相对较少，但随着离心率增加数量增多。在E81、E90和E110时，神经节细胞的树突分支在面积和复杂性上都有所增加，但仅占据IPL总深度的相对较小百分比。在这些胎儿期遇到的双分层细胞通常位于视网膜的远周边区域。在E125 - E140之间，单个神经节细胞的树突分支在面积和深度上增加，比早期胎儿期占据IPL的比例更大。这些观察结果表明，猕猴的神经节细胞经历至少三个树突分层阶段：（1）树突生长的初始阶段，在此期间细胞具有单分层或双分层树突分支；（2）通过细胞死亡或分支重塑，大多数双分层细胞消失；（3）分支生长或扩展以占据IPL总深度的更大百分比。前两个阶段与最近在胎猫中的观察结果相似（Maslim & Stone，1988），不同之处在于灵长类动物的树突发育缺乏向IPL的初始弥漫性向内生长。此外，灵长类神经节细胞在胎儿后期发育中经历树突生长的第三阶段，在此期间分支占据IPL深度的更大比例。
