title: Melanocytes and iris color. Light microscopic findings.
abstract: OBJECTIVE
  To systematically evaluate morphologic differences in iris stroma that contribute to clinically perceptible differences in iris color, using immunohistochemical identification of stromal melanocytes and fluorescence microscopy.
  
  
  METHODS
  Paraffin-embedded sections from 51 human irides were stained with S100a and fluorescein isothiocyanate. Cells were counted and scored as melanocytes or other. Melanocyte number, proportion, and density were determined for light-colored (blue), medium-colored (hazel) and dark-colored (brown) irides and compared.
  
  
  RESULTS
  No statistically significant difference was observed for mean total cellularity or mean melanocyte number among the three color groups. Mean total stromal cell count was 1177 +/- 259 (mean +/- SEM), and mean melanocyte number was 778 +/- 196 per 5-micrometer section. In human irides, 65.9% of the iris stroma is composed of melanocytes. Melanocyte density (number of cells per square millimeter) is not related to iris color.
  
  
  CONCLUSIONS
  The number of melanocytes, the proportion of melanocytes, and iris stromal cellularity are not major contributors to iris color.
authors.affiliation: Departments of Ophthalmology and Visual Sciences, University of Wisconsin Medical School, Madison, USA.
authors.forename: C L
authors.initials: CL
authors.lastname: Wilkerson
authors.forename: N A
authors.initials: NA
authors.lastname: Syed
authors.forename: M R
authors.initials: MR
authors.lastname: Fisher
authors.forename: N L
authors.initials: NL
authors.lastname: Robinson
authors.forename: I H
authors.initials: IH
authors.lastname: Wallow
authors.forename: D M
authors.initials: DM
authors.lastname: Albert
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002452:Cell Count; D005127:Eye Color; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D007498:Iris / Q000166:cytology*; D008297:Male; D008543:Melanins / Q000032:analysis; D008544:Melanocytes / Q000166:cytology*; D011680:Pupil / Q000502:physiology; D009418:S100 Proteins / Q000032:analysis
chemical_list: D008543:Melanins; D009418:S100 Proteins