title: Perivascular mural cells of the mouse choroid demonstrate morphological diversity that is correlated to vasoregulatory function.
abstract: OBJECTIVE
  Perivascular mural cells of the choroid have been implicated in physiological functioning as well as in retinal disease pathogenesis. However details regarding their form and function are not well understood. We aim to characterize choroidal mural cells in the adult mouse choroid in terms of their distribution and morphology, and correlate these to their contractile behavior.
  
  
  METHODS
  Sclerochoroidal flat-mounted explants were prepared from albino transgenic mice in which the α-smooth muscle actin (α-SMA) promoter drives the expression of green fluorescent protein (GFP). α-SMA-expressing smooth muscle cells and pericytes in the living choroid were thereby rendered fluorescent and imaged with confocal microscopy and live-cell imaging in situ.
  
  
  RESULTS
  Choroidal perivascular mural cells demonstrate significant diversity in terms of their distribution and morphology at different levels of the vasculature. They range from densely-packed circumferentially-oriented cells that provide complete vascular coverage in primary arteries to widely-spaced stellate-shaped cells that are distributed sparsely over terminal arterioles. Mural cells at each level are immunopositive for contractile proteins α-SMA and desmin and demonstrate vasoconstrictory contractile movements in response to endothelin-1 and the calcium ionophore, A23187, and vasodilation in response to the calcium chelator, BAPTA. The prominence of vasoregulatory contractile responses varies with mural cell morphology and density, and is greater in vessels with dense coverage of mural cells with circumferential cellular morphologies. In the choriocapillaris, pericytes demonstrate a sparse, horizontal distribution and are selectively distributed only to the scleral surface of the choriocapillaris.
  
  
  CONCLUSIONS
  Diversity and regional specialization of perivascular mural cells may subserve varying requirements for vasoregulation in the choroid. The model of the α-SMA-GFP transgenic albino mouse provides a useful and intact system for the morphological and functional study of choroidal mural cells.
authors: Unit on Neuron-Glia Interactions in Retinal Disease, National Eye institute, National Institutes of Health, Bethesda, Maryland, United States of America.
authors: Audrey B
authors: AB
authors: Condren
authors: Anil
authors: A
authors: Kumar
authors: Pradeep
authors: P
authors: Mettu
authors: Katharine J
authors: KJ
authors: Liang
authors: Lian
authors: L
authors: Zhao
authors: Jen-yue
authors: JY
authors: Tsai
authors: Robert N
authors: RN
authors: Fariss
authors: Wai T
authors: WT
authors: Wong
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism; D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D061207:Calcium Ionophores / Q000494:pharmacology; D002196:Capillaries / Q000187:drug effects; D048430:Cell Shape / Q000502:physiology*; D002614:Chelating Agents / Q000494:pharmacology; D002829:Choroid / Q000098:blood supply / Q000187:drug effects* / Q000648:ultrastructure; D003893:Desmin / Q000235:genetics / Q000378:metabolism; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D019332:Endothelin-1 / Q000494:pharmacology; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins; D051379:Mice; D008822:Mice, Transgenic; D008856:Microscopy, Fluorescence; D009119:Muscle Contraction / Q000187:drug effects; D020286:Pericytes / Q000187:drug effects / Q000648:ultrastructure*; D012590:Sclera / Q000098:blood supply / Q000187:drug effects* / Q000648:ultrastructure; D046509:Tissue Culture Techniques; D014661:Vasoconstriction / Q000187:drug effects*; D014664:Vasodilation / Q000187:drug effects*
chemical_list: D000199:Actins; D061207:Calcium Ionophores; D002614:Chelating Agents; D003893:Desmin; D019332:Endothelin-1; C544013:alpha-smooth muscle actin, mouse; D049452:Green Fluorescent Proteins; D000001:Calcimycin; D004533:Egtazic Acid; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid