Assistant Laboratory Animal Technician (ALAT) Practice Exam

An inbred strain of mice is established after how many brother-sister matings?

1. 10

2. 15

3. 20

4. 25

The correct answer is: 20

The establishment of an inbred strain of mice typically requires a series of sibling matings to achieve a high degree of genetic uniformity. Generally, it is accepted that approximately 20 rounds of brother-sister matings are needed to attain a stable inbred line. This process helps in maximizing homozygosity, where the genetic variants at each locus are the same, leading to a consistent genetic background that is crucial for experimental reproducibility. The number of matings allows for the gradual elimination of heterozygous alleles, establishing a uniform genetic strain suitable for research while minimizing genetic drift.