title: Subtype-specific expression of Fgf19 during horizontal cell development of the chicken retina.
abstract: The mechanisms underlying retinal cell diversification are crucial to proper neural development. Fibroblast growth factor 19 (Fgf19) is expressed by developing horizontal cells (HCs) in the chicken retina. Although there are two major HC subtypes, axon-bearing and axon-less, the precise subtype expressing Fgf19 remains uncertain. Here we characterize Fgf19-expressing cells by co-labeling with antibodies against Lim1 (LIM homeodomain 1, or Lhx1), Islet1, and Prox1 (prospero-related homeobox 1) which are axon-bearing HC, axon-less HC, and pan-HC markers, respectively. We found that a subset of Fgf19-expressing cells was positive for Prox1 and Lim1 in the vitread neuroepithelium at embryonic day 4 (E4). By E9, the majority of Fgf19-expressing cells became positive for Prox1 and Lim1 prior to arrival at the prospective HC layer. In contrast, Fgf19-expressing cells did not overlap with the Islet1-positive population at any stage examined. These results suggest that Fgf19 is expressed by the early migratory horizontal precursors, and later by the presumptive axon-bearing HCs.
authors.affiliation: Department of Life Systems, Institute of Technology and Science, The University of Tokushima Graduate School, 2-1 Minami-Jyosanjima, Tokushima 770-8506, Japan.
authors.forename: Mayumi
authors.initials: M
authors.lastname: Okamoto
authors.forename: Takaaki
authors.initials: T
authors.lastname: Bito
authors.forename: Sumihare
authors.initials: S
authors.lastname: Noji
authors.forename: Hideyo
authors.initials: H
authors.lastname: Ohuchi
mesh_terms: D000818:Animals; D002465:Cell Movement; D002642:Chick Embryo; D002645:Chickens; D005346:Fibroblast Growth Factors / Q000235:genetics* / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000378:metabolism; D017403:In Situ Hybridization; D012160:Retina / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D051248:Retinal Horizontal Cells / Q000378:metabolism*; D013997:Time Factors; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D000098551:Prospero-Related Homeobox 1 Protein
chemical_list: D018398:Homeodomain Proteins; D025521:Tumor Suppressor Proteins; D000098551:Prospero-Related Homeobox 1 Protein; D005346:Fibroblast Growth Factors