On the Occurrence in the House Mouse of Mendelizing Structural Defect of the Retina Producing Blindness

Abstract

This ophthalmic anomaly is characterized histologically by complete absence of rod and external molecular layers and the reduction of the external nuclear layer to a single row of cells. The condition is unidentifiable save by microscopic study of retinal sections prepared by histological technique. Experiments on animal behavior reveal that mice bearing the deficient retinae are totally blind. The character is equally represented in both sexes in all crosses, showing that it is neither sex-linked nor sex-limited. It breeds as a simple recessive mendelizing unit character. Breeding data show no lethal tendency in animals bearing the mutant eye. Linkage tests indicate free segregation with all of the 9 autosomal groups tested. This leads to the conclusion that the determiner for the character lies in a new linkage group. Two new types of eye, bearing about 3 and 6 rows of nuclei in the external nuclear layer respectively, have arisen from an out-cross. Embryological studies indicate that the character is due to an arrest in differentiation of retinal tissues.