Abstract
Purpose: :
To follow with electron microscopy the spatial and temporal features of basal laminar deposits developing in mice following immunization with carboxyethylpyrrole (CEP)-adducted mouse serum albumin (MSA).
Methods: :
Mice were immunized with 200 micrograms of CEP-MSA. Control mice were immunized with non-adducted MSA. After 6-14 months, the mice were sacrificed and processed for analysis. For electron microscopy, eyes were fixed in 2% glutaraldehyde, 2% formaldehyde in 0.1 M cacodylate buffer overnight and postfixed in 1% osmium tetroxide, dehydrated and transferred to Polybed 812 and Araldite 502 with polymizer. Hardened blocks were thin sectioned on an RMC, MT-XL ultramicrotome, placed on nickel grids, stained with uranyl acetate and lead citrate and viewed in a Tecnai 20, 200 kV digital electron microscope equipped with a Gatan image filter.
Results: :
Control mice at 6-14 months have normal basal infoldings; immunized mice show flocculent accumulation of material between the basal lamina, electron dense membranes and a 2-3 fold increase in the thickness of Bruchs membrane was evident. Electron dense granular material was occasionally present in Bruchs membrane and evidence of cellular invasion of this usually cell-free lamina was also seen. Swelling of the outer portion of Bruchs membrane was also present.
Conclusions: :
Immunization of CEP-MSA is sufficient to cause drusen formation in basal laminar deposits below the retinal pigment epithelium. We hypothesize that this immunization raises CEP production in the RPE, which stimulates these cells to elaborate this basal lamina debris.
Keywords: age-related macular degeneration • pathology: experimental • microscopy: electron microscopy