Distribution and morphology of human cone photoreceptors stained with anti-blue opsin.
Primate cones maximally sensitive to short wavelength light (blue cones) have been previously identified by using indirect methods. We stained 7 wholemounted human retinas obtained from 6 female donors, using an affinity purified antibody to a 19 amino acid peptide sequence at the N-terminus of blue opsin (Lerea et al., '89: Neuron 3:367-376), standard PAP immunocytochemistry, and controls. Cones were counted where all outer segments could be traced to inner segments and were measured where cells were well aligned vertically. We find that: (1) 7% of cones within 4 mm of the foveal center are labeled by antiblue opsin; (2) compared to neighboring red/green cones, blue cone inner segments are 10% taller, have a larger cross-sectional diameter near the junction with the outer segment, and a smaller diameter near the external limiting membrane, resulting in a more cylindrical shape, (3) foveal blue cones are sparse, irregularly spaced, and missing in a zone about 100 microns (0.35 degrees) in diameter near the site of peak cone density, (4) the highest densities of blue cones (greater than 2,000 cells/mm2) are found in a ring at 0.1-0.3 mm eccentricity, and (5) the shortest distances between neighboring cones are between blue and red/green cones, and the blue and red/green mosaics are statistically independent. These findings are consistent with psychophysical reports of foveal tritanopia and maximum sensitivity to blue light at 1 degree eccentricity. Blue cone spacing may limit resolution of the blue channel out to 20-30 degrees eccentricity. The blue and red/green mosaics appear to be formed by separate processes.
Curcio
C A
CA
Department of Ophthalmology, University of Alabama, Birmingham 35294.
Allen
K A
KA
Sloan
K R
KR
Lerea
C L
CL
Hurley
J B
JB
Klock
I B
IB
Milam
A H
AH
D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology; D000906:Antibodies / Q000276:immunology; D003196:Computer Graphics; D005260:Female; D006801:Humans; D008875:Middle Aged; D008954:Models, Biological; D010786:Photoreceptor Cells / Q000276:immunology / Q000648:ultrastructure*; D012160:Retina / Q000648:ultrastructure; D013194:Staining and Labeling
D000906:Antibodies