title: Peripapillary glial cells in the chick retina: A special glial cell type expressing astrocyte, radial glia, neuron, and oligodendrocyte markers throughout development.
abstract: Peripapillary glial cells of the chick are a special type of glia, not only because of their position, forming a boundary between the retina on one side and the optic nerve head (ONH) and the pecten on the other, but also because although they have the same orientation and similar shape as the retinal Müller cell (a type of radial glia) and express common markers for these cells and astrocytes, they do not express glutamine synthetase (GS) or carbonic anhydrase C (CA-C), enzymes intensely expressed by Müller cells and astrocytes. In this study, we present further molecular characterization of these cells, using immunohistochemistry techniques. We show that peripapillary glial cells express a novel neuron antigen, 3BA8, that in the adult retina is located only in one neuron type (the amacrine cell) and in the inner plexiform layer (IPL). They also express an antigen specific to myelin and oligodendrocytes, MOSP, and a glial antigen, 3CB2, expressed by radial glia and astrocytes throughout the CNS. The study of the developmental expression of these three antigens in the peripapillary glial cell territory shows different spatiotemporal labeling patterns: 3CB2 and 3BA8 are expressed much earlier (embryonic days E3 and E5, respectively) than MOSP (E12), and during a developmental window (E6-E10) 3BA8 labels the peripapillary glial cells intensely and does not label the ONH or the optic nerve (ON), which are labeled later. The expression of 3CB2 is much more intense in the peripapillary glial cells than in Müller cells from early stages of development up to E16, and the expression of MOSP starts earlier in the peripapillary glial cells than in the Müller cells and is maintained with much higher intensity in the peripapillary glial cells throughout development. These findings show that Müller and peripapillary glial cells follow independent courses of differentiation, which together with the fact that the peripapillary glial cells express molecules typical of neurons, oligodendrocytes, radial glia, and astrocytes are evidence that peripapillary glial cells are a unique type of glia in the CNS.
authors.affiliation: Departamento de Ciencias Morfológicas e Instituto de Biología del Desarrollo, Facultad de Medicina, Universidad de Sevilla, Sevilla, Spain. aquesada@us.es
authors.forename: Adela
authors.initials: A
authors.lastname: Quesada
authors.forename: Francisco A
authors.initials: FA
authors.lastname: Prada
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Aguilera
authors.forename: Auxiliadora
authors.initials: A
authors.lastname: Espinar
authors.forename: Amparo
authors.initials: A
authors.lastname: Carmona
authors.forename: Carmen
authors.initials: C
authors.lastname: Prada
mesh_terms: D025042:Amacrine Cells / Q000378:metabolism; D000818:Animals; D000943:Antigens, Differentiation / Q000096:biosynthesis*; D000954:Antigens, Surface / Q000378:metabolism; D001253:Astrocytes / Q000166:cytology / Q000378:metabolism; D015415:Biomarkers; D002196:Capillaries / Q000166:cytology; D002454:Cell Differentiation / Q000502:physiology*; D048429:Cell Size / Q000502:physiology; D002642:Chick Embryo; D007150:Immunohistochemistry; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009457:Neuroglia / Q000166:cytology / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D009836:Oligodendroglia / Q000166:cytology / Q000378:metabolism; D009900:Optic Nerve / Q000378:metabolism; D012160:Retina / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*
chemical_list: D000943:Antigens, Differentiation; D000954:Antigens, Surface; D015415:Biomarkers; D009419:Nerve Tissue Proteins