title: Nonapical symmetric divisions underlie horizontal cell layer formation in the developing retina in vivo.
abstract: Symmetric cell divisions have been proposed to rapidly increase neuronal number late in neurogenesis, but how critical this mode of division is to establishing a specific neuronal layer is unknown. Using in vivo time-lapse imaging methods, we discovered that in the laminated zebrafish retina, the horizontal cell (HC) layer forms quickly during embryonic development upon division of a precursor cell population. The precursor cells morphologically resemble immature, postmitotic HCs and express HC markers such as ptf1a and Prox1 prior to division. These precursors undergo nonapical symmetric division at the laminar location where mature HCs contact photoreceptors. Strikingly, the precursor cell type we observed generates exclusively HCs. We have thus identified a dedicated HC precursor, and our findings suggest a mechanism of neuronal layer formation whereby the location of mitosis could facilitate rapid contact between synaptic partners.
authors.affiliation: Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors.forename: Leanne
authors.initials: L
authors.lastname: Godinho
authors.forename: Philip R
authors.initials: PR
authors.lastname: Williams
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Claassen
authors.forename: Elayne
authors.initials: E
authors.lastname: Provost
authors.forename: Steven D
authors.initials: SD
authors.lastname: Leach
authors.forename: Maarten
authors.initials: M
authors.lastname: Kamermans
authors.forename: Rachel O L
authors.initials: RO
authors.lastname: Wong
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D019521:Body Patterning / Q000502:physiology; D002454:Cell Differentiation / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D048430:Cell Shape / Q000502:physiology; D049452:Green Fluorescent Proteins / Q000235:genetics; D018398:Homeodomain Proteins / Q000378:metabolism; D008164:Luminescent Proteins / Q000235:genetics; D018613:Microscopy, Confocal; D009434:Neural Pathways / Q000166:cytology* / Q000196:embryology* / Q000502:physiology; D038081:Organogenesis / Q000502:physiology; D020419:Photoreceptor Cells, Vertebrate / Q000166:cytology / Q000502:physiology; D012160:Retina / Q000166:cytology / Q000196:embryology*; D051248:Retinal Horizontal Cells / Q000166:cytology* / Q000196:embryology* / Q000502:physiology; D013234:Stem Cells / Q000166:cytology* / Q000502:physiology; D013569:Synapses / Q000502:physiology / Q000648:ultrastructure; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D015027:Zebrafish; D000098551:Prospero-Related Homeobox 1 Protein
chemical_list: D015415:Biomarkers; D018398:Homeodomain Proteins; D008164:Luminescent Proteins; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D000098551:Prospero-Related Homeobox 1 Protein; C062602:transcription factor PTF1; D049452:Green Fluorescent Proteins