A comparison of fertility assessment and cytogenetic analysis for the detection of translocation heterozygotes in CD-1 mice.

A comparison of the fertility and cytogenetic analyses and the combination of both techniques as generally used in the heritable translocation assay was conducted with triethylenemelamine (TEM). CD-1 mice were used as the F0 generation and were divided into two groups that received i.p. either distilled water (control) or TEM at 0.15-0.20 mg/kg. A total of 226 F1 males were generated (125 control, 101 TEM group) and were subjected to both sequential fertility assessment and direct cytogenetic analysis. A litter size of 10 was used for the fertility assessment method and 25 cells per animal were scored for the direct cytogenetic analysis; 20 animals were initially identified as translocation carriers based on the fertility analysis and 16 animals were identified by cytogenetic analysis. When these data were compared and the discrepancies resolved, each method separately identified 16 translocation carriers (15 animals common to both methods). With the combination of data for both techniques, as is done in the heritable translocation assay, a total of 17 translocation heterozygotes were identified. Use of either the fertility method alone or the cytogenetic method as routinely used would have resulted in the separate identification of 16 translocation carriers per procedure, with each method failing to identify one carrier.