Using cuprolinic blue staining, we histochemically examined the ultras
tructural localization of proteoglycans in the fibrous-type human post
erior capsule opacification. This capsule opacification contained prot
eoglycans that showed positive staining with cuprolinic blue. Many cup
rolinic-blue-positive filaments were present within the bundles of col
lagen fibrils, basal lamina-like material and basal lamina of prolifer
ated lens epithelial cells. Pretreatment with enzymes and nitrous acid
revealed that the collagen fibrils contained chondroitin sulfate and
dermatan sulfate, whereas the basal lamina-like material and basal lam
ina of epithelial cells contained heparan sulfate. These results sugge
st that proteoglycans are one of the components in posterior capsule o
pacification.