Robinson S R, Dreher B, McCall M J
Department of Anatomy, University of Sydney.
Vis Neurosci. 1989;2(3):201-19. doi: 10.1017/s0952523800001139.
We have studied the distribution of retinal ganglion cells (RGCs) which have been retrogradely labeled from massive bilateral injections of the enzyme horseradish peroxidase into the retino-recipient nuclei of foetal and postnatal albino rabbits aged from the 24th postconceptional day (24PCD) to adulthood. The number of labeled RGCs increases from about 447,000 on the 24PCD to a peak of about 525,000 on the 27PCD. From the 29PCD to birth (31/32PCD), the number of RGCs rapidly declines to about 375,000. During the next 20 d, the number of RGCs stabilizes at about 335,000. After the 51PCD, the number of RGCs gradually declines to the adult value of about 280,000. Retinal area steadily increases from about 40 mm2 on the 24PCD to about 500 mm2 in the adult, while RGC density decreases. However, the reduction in RGC density is nonuniform: RGC density in the visual streak drops from 18,600 RGCs mm2 on the 24PCD to 4700 RGCs/mm2 in the adult, whereas RGC densities at the superior and inferior edges of the retina decreases proportionally much more (from 9300 to 105 RGCs/mm2 and from 12,000 to 170 RGCs/mm2, respectively). As a result of this differential reduction in RGC density, the streak/inferior edge ratio changes from 1.6:1 to about 28:1. In the periods from the 24PCD to the 29PCD and from the 32PCD to adulthood, the proportional increases in the streak/superior edge and streak/inferior edge RGC density ratios are linearly related to the proportional increases in retinal area. However, between the 29PCD and 32PCD, the RGC density ratios increase at a greater rate than retinal area. We conclude that (1) the centro-peripheral difference in RGC density that is already present on the 24PCD might be attributable to differential RGC generation; (2) the redistribution of RGCs between the 24PCD and adulthood is mainly due to nonuniform expansion of the retina, with minimal expansion of the visual streak and maximal expansion at the superior and inferior retinal edges; and (3) a small component of the increase in the centro-peripheral RGC density ratio, which becomes apparent between the 29PCD and 32PCD, is probably due to differential RGC loss. We discuss the pattern of retinal expansion in the rabbit and the factors which might contribute to it.
我们研究了视网膜神经节细胞（RGCs）的分布情况，这些细胞是通过将辣根过氧化物酶大量双侧注射到受孕后第24天（24PCD）至成年期的胎儿和新生白化兔的视网膜接受核中进行逆行标记的。标记的RGCs数量从24PCD时的约447,000个增加到27PCD时的峰值约525,000个。从29PCD到出生（31/32PCD），RGCs数量迅速下降至约375,000个。在接下来的20天里，RGCs数量稳定在约335,000个。51PCD后，RGCs数量逐渐下降至成年时的约280,000个。视网膜面积从24PCD时的约40mm²稳步增加到成年时的约500mm²，而RGC密度降低。然而，RGC密度的降低并不均匀：视带中的RGC密度从24PCD时的18,600个/mm²降至成年时的4700个/mm²，而视网膜上下边缘的RGC密度下降比例更大（分别从9300个降至105个/mm²和从12,000个降至170个/mm²）。由于RGC密度的这种差异降低，视带/下边缘比率从1.6:1变为约28:1。在从24PCD到29PCD以及从32PCD到成年期的时间段内，视带/上边缘和视带/下边缘RGC密度比率的比例增加与视网膜面积的比例增加呈线性相关。然而，在29PCD和32PCD之间，RGC密度比率的增加速度比视网膜面积快。我们得出结论：（1）24PCD时就已存在的RGC密度的中心 - 周边差异可能归因于RGC生成的差异；（2）24PCD和成年期之间RGCs的重新分布主要是由于视网膜的不均匀扩张，视带扩张最小，视网膜上下边缘扩张最大；（3）在29PCD和32PCD之间变得明显的中心 - 周边RGC密度比率增加的一小部分可能是由于RGC的差异丢失。我们讨论了兔子视网膜扩张的模式以及可能导致这种扩张的因素。
