Analysis of quantitative inheritance of body size in mice IV. An Attempt to isolate polygenes

Abstract

The isolation of single inheritance units affecting body size in mice has been attempted. By using Large and Small mice as the parental strains, a breeding scheme has been carried out by repeated backcrossing to each strain with selection for both large and small body sizes in each backcross. The selections were started from the second backcross generations. The Small backcross was carried to the seventh generation and the Large to the fifth. Based on analysis of the means and variances for the parental strains and the backcross generations, it is tentatively concluded that a small number of, if not single, inheritance units may have been introduced from the Large to the Small mice. The ‘large’ genes appear to be dominant over the ‘small’ genes.