Abstract：
The fovea is a small region within the central retina that is responsible for our high acuity daylight vision. Chickens also have a high acuity area (HAA), and are one of the few species that enables studies of the mechanisms of HAA development, due to accessible embryonic tissue and methods to readily perturb gene expression. To enable such studies, we characterized the development of the chick HAA using single molecule fluorescent in situ hybridization (smFISH), along with more classical methods. We found that Fgf8 provides a molecular marker for the HAA throughout development and into adult stages, allowing studies of the cellular composition of this area over time. The radial dimension of the ganglion cell layer (GCL) was seen to be the greatest at the HAA throughout development, beginning during the period of neurogenesis, suggesting that genesis, rather than cell death, creates a higher level of retinal ganglion cells (RGCs) in this area. In contrast, the HAA acquired its characteristic high density of cone photoreceptors post-hatching, which is well after the period of neurogenesis. We also confirmed that rod photoreceptors are not present in the HAA. Analyses of cell death in the developing photoreceptor layer, where rods would reside, did not show apoptotic cells, suggesting that lack of genesis, rather than death, created the \"rod-free zone\" (RFZ). Quantification of each cone photoreceptor subtype showed an ordered mosaic of most cone subtypes. The changes in cellular densities and cell subtypes between the developing and mature HAA provide some answers to the overarching strategy used by the retina to create this area and provide a framework for future studies of the mechanisms underlying its formation.
摘要：
中央凹是中央视网膜内的一个小区域，负责我们的高敏锐度日光视觉。鸡也有高敏锐度区（HAA），是少数能够研究HAA发育机制的物种之一，由于可接近的胚胎组织和容易扰乱基因表达的方法。为了进行此类研究，我们使用单分子荧光原位杂交（smFISH）表征了小鸡HAA的发展，以及更经典的方法。我们发现Fgf8在整个发育和成虫阶段为HAA提供了分子标记，允许随着时间的推移研究该区域的细胞组成。在整个发育过程中，神经节细胞层（GCL）的径向尺寸在HAA中最大，从神经发生时期开始，这表明创世纪，而不是细胞死亡，在该区域产生更高水平的视网膜神经节细胞（RGCs）。相比之下,HAA在孵化后获得了其特有的高密度视锥光感受器，这是在神经发生期之后。我们还证实了杆状光感受器不存在于HAA中。分析正在发育的感光层中的细胞死亡，棒将驻留的地方，没有显示凋亡细胞，表明缺乏起源，而不是死亡，创建了“无杆区域”(RFZ)。每个视锥感光亚型的定量显示大多数视锥亚型的有序镶嵌。发育中和成熟的HAA之间的细胞密度和细胞亚型的变化为视网膜用于创建该区域的总体策略提供了一些答案，并为其形成机制的未来研究提供了框架。
