Sterol profile in the retina and serum of C57BL/6J (WT) and Apoe−/− mice. Retinal levels of cholesterol (A), lathosterol and desmosterol (B), as well as 24-hydroxycholesterol (24HC) and 5-cholestenoic acid (5CA) (C) in female and male mice on regular chow and WTD fed for 5 months (from 1 to 6 months of age). Serum levels of cholesterol (D), lathosterol and desmosterol (E), as well as 24HC (F) in female and male mice on regular chow and Western diet. Results are means ± SD; n, number of mice. For retinal cholesterol, lathosterol, desmosterol, and 24HC measurements, number of mice equals the number of retinas; for 5CA measurements, three and four samples for C57BL/6J and Apoe−/− genotypes, respectively, were individually quantified, each containing two retinas from three or four mice. Significance was calculated using a two-tailed, unpaired Student’s t-test. ** P ≤ 0.01; *** P ≤ 0.001. EC, esterified cholesterol.