Comparison of two methods for detecting translocation heterozygotes in mice

An accurate estimate of the error of misclassifying male translocation heterozygotes as normals is essential for the proper evaluation of results of the heritable translocation test in mice. The size of this error may vary from one laboratory to another depending, primarily, on the method or variation of the method used in screening for translocation heterozygotes. This report shows a way to estimate for misclassification errors involved in two methods, sequential and direct cytological analysis, of screening for translocation heterozygotes. A positive correlation was found between the degree of partial sterility of a male and the frequency of cells with multivalent configurations among his diakinesis-metaphase I cells. We interpreted this to confirm that the length of translocated chromosome segments has some influence on the proportion of unbalanced gametes in the ejaculate, presumably reflecting the frequency with which adjacent-1 and adjacent-1 segregations and 3-1 misdivisions occur.