Fig. 4. Quantification of photoreceptor outer segment length and rhodopsin staining density within the outer segment in wild type and IFT57 mutants. (A) IFT57 mutant photoreceptor outer segments are reduced in length by 75% when compared with age-matched wild-type photoreceptors. Data were taken from retinas of four animals for both wild type and IFT mutants. (B) Photoreceptor outer segments in IFT57 mutants contain 59% less rhodopsin. Staining density was determined by counting colloidal gold particles in a random 0.25 µm² region of rod outer segments with each data point obtained from a unique outer segment. Data were obtained from retinas of four animals for both wild type and IFT57 mutants. (A) P<0.01, (B) P<0.0001, as determined by a Student's t-test.