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

在视觉生态学的背景下，脊椎动物视网膜是研究复杂感觉器官结构-功能相关性及其物种特异性适应的主要例子。外视网膜（色素上皮+光感受器）的组织学和精细结构指示了视力、灵敏度和对比机制（如光感受器形态），这必须通过细胞数量比和内视网膜的神经解剖学结果来指定。对神经元网络的结构和功能的基本理解，以及对变化（例如单色，二色，三色，四色对比度形成）的见解，都与所有细胞类型的形状和布线规则的高分辨率结构数据的可用性和质量有关-这些贡献可以通过光学和电子显微镜3D成像从形态学视网膜研究中得到越来越好的结果。然而，视网膜连接组学的“突破”是采用机械切割（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，它首次为我们提供了几乎无畸变的超薄层系列，用于纳米分辨率的整个神经元网络的3D重建和形态测量。在之前的项目中，我们首次使用FIB-FESEM研究了硬骨鱼视网膜的多种细胞类型和一些连接规则，并证明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，我们将尽可能完整地研究4种具有不同视网膜连接方案的硬骨鱼物种的连接体。为此，应结合FIB-FESEM（用于外丛状层的极细分支）和Heidelberger Hobel（用于剩余的内视网膜包括内丛状层）。

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.