The Transgenic Rodent (TGR) Mutation Assays can detect chemicals that induce point mutations and small deletions (as opposed to gross chromosomal damage/loss) in somatic and germ cells in vivo. TGR mutation models contain transgenic reporter genes that are carried on vectors designed to be easily recovered from any tissue in the body. Mutations arising in a rodent are measured by recovering and analyzing the phenotype of the reporter gene in a bacterial host deficient for the reporter gene.

Muta™小鼠是一种转基因小鼠模型，其染色体3. DNA与感兴趣的组织分离的单个轨迹中的LacZ报告器基因的多个副本，然后切除报告基因并插入噬菌体颗粒中。将它们与大肠杆菌细菌一起孵育，缺乏功能性lacz基因和功能性大孔基因（gale-，lacz-）。细菌在选择性培养基上生长，这些培养基对Gale-，Lacz-细菌有毒。只有受背部突变的功能性LacZ +基因的细菌可以存活。突变频率可以通过在选择性培养基上生长的细菌菌落数与非选择性培养基上的比率估算。