title: Assessment of size and nucleo-cytoplasmic characteristics of the squamous cells of the corneal epithelium.
abstract: OBJECTIVE
  The aim was to objectively assess size, nucleus and nucleo-cytoplasmic ratio features of squamous cells from the corneal epithelium
  
  
  METHODS
  The corneas of recent post-mortem sheep eyes were either glutaraldehyde-fixed for transmission electron microscopy or impression cytology samples taken, glutaraldehyde-fixed and stained with Giemsa. From the specimens for impression cytology, a representative region was photographed from 12 different samples taken from the central region and 16 different samples taken from mid-peripheral regions of the corneal epithelium. Images were subjected to morphometry after overlays were generated.
  
  
  RESULTS
  Electron microscopy revealed a very distinctive stratified corneal epithelium with several superficial layers, confirming the squamous phenotype. Impression cytology from such superficial layers revealed a cell size of 60.1 ± 4.8 μm, nucleus dimension of 12.3 ± 1.5 μm, cell area of 2,419 ± 416 μm(2) and nucleus area of 131 ± 31 μm(2) . A nucleo-cytoplasmic ratio based on nucleus-to-cell length had a mean of 0.207 ± 0.022, while a cytoplasm-to-nucleus length ratio was 3.975 ± 0.474. Estimates of the nucleo-cytoplasmic ratio based on areas had a mean value of 0.059 ± 0.011. Very similar results were found for mid-peripheral corneal epithelium.
  
  
  CONCLUSIONS
  The results strongly indicate that the squamous phenotype of the superficial corneal epithelial cells is characterised by a large size, large nucleus and low nucleo-cytoplasmic ratio. These morphological characteristics show a notable resemblance to data obtained from impression cytological studies on human conjunctival epithelial cells showing severe squamous metaplasia.
authors: Department of Vision Sciences, Glasgow-Caledonian University, Glasgow, G4 OBA, UK. m.doughty@gcal.ac.uk.
authors: Michael J
authors: MJ
authors: Doughty
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000648:ultrastructure*; D048429:Cell Size; D003316:Corneal Diseases / Q000473:pathology; D003593:Cytoplasm / Q000648:ultrastructure*; D004195:Disease Models, Animal; D004847:Epithelial Cells / Q000648:ultrastructure*; D019573:Epithelium, Corneal / Q000648:ultrastructure*; D008679:Metaplasia / Q000473:pathology; D046529:Microscopy, Electron, Transmission / Q000379:methods*; D012756:Sheep
keywords: N/C ratio; corneal epithelium; impression cytology; morphometry; squamous cells; transmission electron microscopy