BACKGROUND Melanopsin-expressing, intrinsically photosensitive retinal ganglion cells (ipRGCs) respond directly to light and have been shown to mediate a broad variety of visual behaviors in adult animals. ipRGCs are also the first light sensitive cells in the developing retina, and have been implicated in a number of retinal developmental processes such as pruning of retinal vasculature and refinement of retinofugal projections. However, little is currently known about the properties of the six ipRGC subtypes during development, and how these cells act to influence retinal development. We therefore sought to characterize the structure, physiology, and birthdate of the most abundant ipRGC subtypes, M1, M2, and M4, at discrete postnatal developmental timepoints. METHODS We utilized whole cell patch clamp to measure the electrophysiological and morphological properties of ipRGC subtypes through postnatal development. We also used EdU labeling to determine the embryonic timepoints at which ipRGC subtypes terminally differentiate. RESULTS Our data show that ipRGC subtypes are distinguishable from each other early in postnatal development. Additionally, we find that while ipRGC subtypes terminally differentiate at similar embryonic stages, the subtypes reach adult-like morphology and physiology at different developmental timepoints. CONCLUSIONS This work provides a broad assessment of ipRGC morphological and physiological properties during the postnatal stages at which they are most influential in modulating retinal development, and lays the groundwork for further understanding of the specific role of each ipRGC subtype in influencing retinal and visual system development.

中文翻译：

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出生后发育过程中本质光敏视网膜神经节细胞的细胞特性。


背景表达黑视蛋白的本质光敏视网膜神经节细胞（ipRGC）直接对光做出反应，并已被证明可以介导成年动物的多种视觉行为。 ipRGC 也是发育中的视网膜中第一个光敏细胞，并且与许多视网膜发育过程有关，例如视网膜脉管系统的修剪和视网膜离断投影的细化。然而，目前人们对六种 ipRGC 亚型在发育过程中的特性以及这些细胞如何影响视网膜发育知之甚少。因此，我们试图表征最丰富的 ipRGC 亚型 M1、M2 和 M4 在离散的出生后发育时间点的结构、生理学和出生日期。方法 我们利用全细胞膜片钳来测量 ipRGC 亚型在出生后发育过程中的电生理和形态学特性。我们还使用 EdU 标记来确定 ipRGC 亚型最终分化的胚胎时间点。结果我们的数据表明，ipRGC 亚型在出生后发育早期是相互区分的。此外，我们发现虽然 ipRGC 亚型在相似的胚胎阶段最终分化，但这些亚型在不同的发育时间点达到类似成人的形态和生理学。结论这项工作对出生后阶段的 ipRGC 形态和生理特性进行了广泛的评估，在该阶段它们对调节视网膜发育最具影响力，并为进一步了解每种 ipRGC 亚型在影响视网膜和视觉系统发育中的具体作用奠定了基础。