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Updated: Aug 12, 2026

Enrichment of Bruch's Membrane from Human Donor Eyes
Published on: November 15, 2015
Distribution of the collagen IV isoforms in human Bruch's membrane
L Chen1, N Miyamura, Y Ninomiya
1Department of Ophthalmology, University of California, Davis, USA.
Aims:
To determine the distribution of the alpha1 to alpha6 chains of type IV collagen in Bruch's membrane of the human posterior pole.
Methods:
Cryosections (10 micro m) from 18 human eyes (20 months to 83 years old) were acid treated, blocked with 10% normal goat serum, incubated for 1 hour with monoclonal antibodies against type IV collagen isoform specific peptides at 1:75 dilution, and visualised with an ABC staining kit.
Results:
In Bruch's membrane, the alpha1(IV) and alpha2(IV) chains were identified in retinal pigment epithelial (10/18 = 55%) and choriocapillaris basement membranes (18/18 = 100%); the alpha3(IV), alpha4(IV), and alpha5(IV) chains were also found in the retinal pigment epithelial basement membrane (13/18 = 72%). In the choroid, the alpha1(IV) and alpha2(IV) chains were detected in the blood vessels (18/18=100%). The alpha6(IV) chain was not identified in any sections.
Conclusion:
The heterogeneous distribution of alpha1-2(IV) and alpha3-5(IV) in Bruch's membrane could give insights into the function of this structure in health, ageing, and diseases such as age related macular degeneration.
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