title: Inhibitory neuron migration and IPL formation in the developing zebrafish retina.
abstract: The mature vertebrate retina is a highly ordered neuronal network of cell bodies and synaptic neuropils arranged in distinct layers. Little, however, is known about the emergence of this spatial arrangement. Here, we investigate how the three main types of retinal inhibitory neuron (RIN)--horizontal cells (HCs), inner nuclear layer amacrine cells (iACs) and displaced amacrine cells (dACs)--reach their specific laminar positions during development. Using in vivo time-lapse imaging of zebrafish retinas, we show that RINs undergo distinct phases of migration. The first phase, common to all RINs, is bipolar migration directed towards the apicobasal centre of the retina. All RINs then transition to a less directionally persistent multipolar phase of migration. Finally, HCs, iACs and dACs each undergo cell type-specific migration. In contrast to current hypotheses, we find that most dACs send processes into the forming inner plexiform layer (IPL) before migrating through it and inverting their polarity. By imaging and quantifying the dynamics of HCs, iACs and dACs from birth to final position, this study thus provides evidence for distinct and new migration patterns during retinal lamination and insights into the initiation of IPL formation.
authors.affiliation: Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK.
authors.forename: Renee W
authors.initials: RW
authors.lastname: Chow
authors.affiliation: Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK.
authors.forename: Alexandra D
authors.initials: AD
authors.lastname: Almeida
authors.affiliation: Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK.
authors.forename: Owen
authors.initials: O
authors.lastname: Randlett
authors.affiliation: MPI of Molecular Cell Biology and Genetics, Pfotenhauerstraße 108, Dresden 01307, Germany norden@mpi-cbg.de wah20@cam.ac.uk.
authors.forename: Caren
authors.initials: C
authors.lastname: Norden
authors.affiliation: Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK norden@mpi-cbg.de wah20@cam.ac.uk.
authors.forename: William A
authors.initials: WA
authors.lastname: Harris
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D002465:Cell Movement / Q000502:physiology*; D007091:Image Processing, Computer-Assisted; D007700:Kinetics; D008856:Microscopy, Fluorescence; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D012160:Retina / Q000196:embryology*; D059008:Time-Lapse Imaging; D015027:Zebrafish / Q000196:embryology*
keywords: Amacrine cells; Displaced amacrine cells; Horizontal cells; Inner plexiform layer; Neuronal migration