High resolution 3D-neuroanatomy of the retina - investigation of wiring rules in different contrast mechanisms

脊椎动物视网膜是在视觉生态学背景下研究复杂感官的结构-功能-相关性及其物种特异性适应的主要例子。外部视网膜的组织学和精细结构(色素上皮+光感受器)表明了视力、敏感度和对比机制(例如，光感受器的形态类型)，这些必须通过视网膜内部的细胞数量比率和神经解剖学发现来确定。两者都是对神经元网络结构和功能的基本了解，以及对各种变化(如单色、双色、三色、四色对比形成)的见解随着所涉及的所有细胞类型的形状和连接规则的高分辨率结构数据的可用性和质量而变化-这些贡献可以通过光学和电子显微镜3D成像从形态视网膜研究中获得越来越好的贡献。然而，视网膜连接学中的“突破”是具有机械切割(Heidelberger Hobel)或离子束铣削(FIB-FESEM)的连续块面扫描电子显微镜(SBFSEM)的最新方法，这些方法首次为我们提供了几乎无失真的超薄层系列，用于在纳米分辨率下对整个神经元网络进行3D重建和形态测量。在之前的项目中，我们首次用FIB-FESEM研究了硬骨视网膜的多种细胞类型和一些连接规则，并论证了这种方法的可能性和局限性。为了克服这些限制，并能够在适当的背景下解释动物学/神经解剖学的发现，将尽可能完整地研究具有不同视网膜连接方案的4种硬骨鱼物种的连接。为此，FIB-FESEM(用于外丛状层的极其精细的分支)和Heidelberger Hobel(用于剩余的内视网膜包括。内部网状层)应合并。

The vertebrate retina is a prime example for the investigation of structure-function-correlations of complex sensory organs and their species-specific adaptation in the context of visual ecology. Histology and fine structure of the outer retina (pigment epithelium + photoreceptors) are indicative for visual acuity, sensitivity and contrast mechanisms (e.g. photoreceptor morphotypes), that have to be specified via cell number ratios and neuroanatomical findings from the inner retina. Both, a fundamental understanding of architecture and function of a neuronal net, and insights about variations (e.g. mono-, di-, tri, tetrachromatic contrast formation) stand and fall with the availability and quality of high resolution structure data of shape and wiring rules of all cell types involved - contributions that can be received better and better from morphological retina research via light- and electron-microscopical 3D imaging. The “break through” within retinal connectomics, however, are the latest methods of serial block face scanning electron microscopy (SBFSEM) with mechanical cutting (Heidelberger Hobel) or ion beam milling (FIB-FESEM), that give us for the first time almost distortion-free ultrathin layer series for 3D reconstruction and morphometry of entire neuronal nets in nm-resolution. In the previous project we investigated numerous cell types and some connectivity rules of a teleost retina with FIB-FESEM for the first time and demonstrated possibilities and limits of this method. To overcome these limits and to be able to interpret the zoological/neuroanatomical findings in an adequate context, the connectoms of 4 teleost species with different retinal connection schemes will be investigated as complete as possible. For this purpose FIB-FESEM (for the extremely fine ramifications of the outer plexiform layer) and the Heidelberger Hobel (for the remaining inner retina incl. inner plexiform layer) shall be combined.