title: Microstructure and network organization of the microvasculature in the human macula.
abstract: OBJECTIVE
  To characterize the topography and cellular structure of the macular microvasculature using a recently developed technique of arterial cannulation, perfusion, fixation, and staining of human donor eyes.
  
  
  METHODS
  Sixteen human donor eyes were used. The central retinal artery was cannulated and perfused with Ringer's, then fixative, membrane permeabilizing, and selected labeling solutions. The eyes were immersion fixed, and the retina was flat mounted for confocal microscopy. The macular area, including the foveola, fovea, and parafovea, was sampled. The intracellular cytoskeleton of vascular endothelial and smooth muscle cells was studied in different orders of arterioles and venules and in the capillaries. To evaluate the degree of asymmetry within vascular networks, the distribution of generation numbers and the Horton-Strahler approach to vessel naming were compared.
  
  
  RESULTS
  The distribution of the microvascular network in the macular region was complex but followed a general theme. The parafoveal region was supplied by dense vasculature with approximately nine closely arranged pairs of arterioles and venules. Each arteriole had abundant branches and a high degree of asymmetry (∼10 generations and 3.5 orders within 1.2-mm length). Only a few arterioles (average ∼2.9) supplied the terminal capillary ring. Very long spindle endothelial cells were seen in the superficial and deep capillaries. Significant heterogeneity of distribution and shape of the endothelial and smooth muscle cells was evident in different orders of the macular vasculature.
  
  
  CONCLUSIONS
  The authors have demonstrated for the first time the cellular structure and topographic features of the macular microvasculature in human donor eyes.
authors.affiliation: Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Australia.
authors.forename: Paula K
authors.initials: PK
authors.lastname: Yu
authors.forename: Chandrakumar
authors.initials: C
authors.lastname: Balaratnasingam
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Cringle
authors.forename: Ian L
authors.initials: IL
authors.lastname: McAllister
authors.forename: Jan
authors.initials: J
authors.lastname: Provis
authors.forename: Dao-Yi
authors.initials: DY
authors.lastname: Yu
mesh_terms: D000328:Adult; D000368:Aged; D001160:Arterioles / Q000033:anatomy & histology*; D004730:Endothelium, Vascular / Q000033:anatomy & histology; D005456:Fluorescent Dyes; D006801:Humans; D008266:Macula Lutea / Q000098:blood supply*; D008297:Male; D008833:Microcirculation; D018613:Microscopy, Confocal; D008875:Middle Aged; D009131:Muscle, Smooth, Vascular / Q000033:anatomy & histology; D011806:Quinolinium Compounds; D012171:Retinal Vessels / Q000033:anatomy & histology*; D013194:Staining and Labeling / Q000379:methods; D014019:Tissue Donors; D014699:Venules / Q000033:anatomy & histology*; D055815:Young Adult
chemical_list: C481052:Alexa fluor 546; D005456:Fluorescent Dyes; D011806:Quinolinium Compounds