[Mutant gene expression in murine aggregation chimeras. 5. The ocular retardation and fidget genes]

Analysis of ocular retardation (or) and fidget (fi) genes expression in 18 day old embryos, 10 and 20 day old or/or C/C----+/+ c/c and fi/fi or/or C/C----+/+ +/+ c/c mice has shown that genes or and fi are active in developing retina and suppress cell proliferation. Structural defects of retina and decrease in the eye size in the chimaeras, compared to the normal embryos, were observed already in the presence of 13-16% of mutant cells. As the fraction of mutant cells increased, the degree of eye disturbances increased as well. In the fi/fi or/or----+/+ +/+ chimaeras structural defects of retina and decrease in the eye size are more pronounced than in the or/or----+/+ chimaeras, due to the synergetical effect of both mutant genes in the fi/fi or/or cell clones. In the ontogenesis of the or/or----+/+ chimaeras the development of the retinal photoreceptor layer is normalized due to the substitution of mutant cells for actively proliferating normal cells. No metabolic cooperation between the mutant and normal cells was observed in the developing retina of chimaeras.