Melanocytes and iris color. Light microscopic findings.
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.
Wilkerson
C L
CL
Departments of Ophthalmology and Visual Sciences, University of Wisconsin Medical School, Madison, USA.
Syed
N A
NA
Fisher
M R
MR
Robinson
N L
NL
Wallow
I H
IH
Albert
D M
DM
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
D008543:Melanins; D009418:S100 Proteins