Villar-Cheda Begoña, Abalo Xesús Manoel, Villar-Cerviño Verona, Barreiro-Iglesias Antón, Anadón Ramón, Rodicio María Celina
Department of Cell Biology and Ecology, University of Santiago de Compostela, 15782-Santiago de Compostela, Spain.
Brain Res. 2008 Mar 27;1201:60-7. doi: 10.1016/j.brainres.2008.01.077. Epub 2008 Feb 11.
Lamprey eyes exhibit dual retinal development, with highly different larval and adult phases. Here, cell proliferation and photoreceptor differentiation was investigated in late larvae and during transformation (occurring several years after egg hatching) by using immunohistochemistry against the proliferating cell nuclear antigen (PCNA) and opsins. In large larvae proliferating cells are mainly located in the lateral retina, a wide undifferentiated region, whereas opsin immunoreactivity revealed only a single type of photoreceptors in the very small central retina. In premetamorphic larvae, retinal cell proliferation increases considerably, but at metamorphosis it becomes progressively restricted to the periphery of the lateral retina. Proliferating (PCNA-immunoreactive) cells were mainly observed in the inner nuclear layer but also in the outer plexiform layer and outer nuclear layer, suggesting that the latter proliferating cells migrate to the outer nuclear layer and differentiate into photoreceptors. In the lateral retina, first photoreceptors expressing opsins were observed at middle metamorphic stages, and outer and inner segments were present at latter stages. Some immature photoreceptors were also observed in postmetamorphic retina. Unlike teleost and amphibian retinas, no proliferating cells were observed in the retina after metamorphosis, indicating that the retinal growth after this period is due to cellular reorganization and increase in cell size.
七鳃鳗的眼睛呈现出双重视网膜发育过程，其幼体期和成体期存在很大差异。在此，通过使用针对增殖细胞核抗原（PCNA）和视蛋白的免疫组织化学方法，对晚期幼体以及变态过程中（在卵孵化几年后发生）的细胞增殖和光感受器分化进行了研究。在大型幼体中，增殖细胞主要位于视网膜外侧，这是一个宽阔的未分化区域，而视蛋白免疫反应仅在非常小的中央视网膜中显示出单一类型的光感受器。在变态前的幼体中，视网膜细胞增殖显著增加，但在变态时，它逐渐局限于视网膜外侧的周边区域。增殖（PCNA免疫反应阳性）细胞主要在内核层中观察到，但在外网状层和外核层中也有，这表明后者的增殖细胞迁移到外核层并分化为光感受器。在视网膜外侧，在变态中期首次观察到表达视蛋白的光感受器，在后期出现了外段和内段。在变态后的视网膜中也观察到一些未成熟的光感受器。与硬骨鱼和两栖动物的视网膜不同，在变态后视网膜中未观察到增殖细胞，这表明在此之后的视网膜生长是由于细胞重组和细胞大小增加所致。
