The experiments were conducted with the approval of the local animal experimentation and ethics committee. Animals were handled according to the guidelines on care and use of experimental animals set forth by the Government Committee on Animal Experimentation at the University of Lund and the ARVO Statement for the Use of Animals in Ophthalmic and Vision Research.
Retinal degeneration 1 (rd1), rds, and corresponding control wild-type (wt) mice were used for studies on the expression of retinal CD11b, Sn, and MHC. Animals were bred on a homozygous background (rd1: C3H/HeA or C57BL6/129; rds: C3H/HeA; and wt: C3H/HeA or C57BL6/129; own colonies), and maintained on a 12-hour light-dark cycle, with free access to food and water. They were killed with carbon dioxide at different ages (rd1: postnatal days (P)7–P150, n = 24; rds: P8–P30, n = 16; and wt: P11–P150, n = 8). Eyes were thereafter quickly enucleated and immersed in a solution of 4% paraformaldehyde (PFA) in Sørensen’s buffer (pH 7.4) for 2 hours at 4°C. The tissue was subsequently rinsed, cryoprotected in the same buffer containing increasing concentrations of sucrose, embedded in an albumin-gelatin medium, frozen, and stored at −20°C. The sections were obtained on a cryostat (12 μm), collected on gelatin/chrome alumcoated glass slides, air-dried, and stored at −20°C until further processing. Some eyes from all groups were enucleated, quickly frozen without prior fixation (n = 8), and stored at −80°C. Retinas from wild-type control mice were also dissected from the pigment epithelium under cold Sørensen’s buffer and transferred to a 3-μm pore filter (Millipore AB, Solna, Sweden) with the photoreceptor side down. The attached flattened retinas were fixed for 5 minutes with 4% PFA and rinsed thereafter with Sørensen’s buffer.