在从人类到蜥蜴的许多物种中,都观察到了眼睛发育过程中眼球大小的明显不对称变化。相比之下,对于其他物种,例如啮齿动物,已经描述了地球大小的基本对称变化。我们认为发育中的眼睛的三维结构的不对称变化与产生高感光体密度区域所需的视网膜重塑类型相关。为了测试这个想法,我们系统地检查了眼球大小的三维方面,作为眼睛发育的函数,AnolisSagrei.
在胚胎发育过程中,anole眼经历眼睛形状的动态变化。最初是球形的,眼睛在假定的视网膜中央凹区域伸长,然后经过一段时间的收缩,使眼睛恢复到球形。在这个撤回期间,观察到凹坑形成和感光细胞堆积。我们发现了类似的伸长和收缩模式,与面纱变色龙的单个中央凹相关,Chamaeleocalyptratus.
这些结果,以及其他中央凹物种的报道,支持高感光体堆积区域发生在眼球在发育过程中不对称伸长和缩回的区域。
Pronounced asymmetric changes in ocular globe size during eye development have been observed in a number of species ranging from humans to lizards. In contrast, largely symmetric changes in globe size have been described for other species like rodents. We propose that asymmetric changes in the three-dimensional structure of the developing eye correlate with the types of retinal remodeling needed to produce areas of high photoreceptor density. To test this idea, we systematically examined three-dimensional aspects of globe size as a function of eye development in the bifoveated brown anole, Anolis sagrei.
During embryonic development, the anole eye undergoes dynamic changes in ocular shape. Initially spherical, the eye elongates in the presumptive foveal regions of the retina and then proceeds through a period of retraction that returns the eye to its spherical shape. During this period of retraction, pit formation and photoreceptor cell packing are observed. We found a similar pattern of elongation and retraction associated with the single fovea of the veiled chameleon, Chamaeleo calyptratus.
These results, together with those reported for other foveated species, support the idea that areas of high photoreceptor packing occur in regions where the ocular globe asymmetrically elongates and retracts during development.