Assistant Laboratory Animal Technician (ALAT) Practice Exam

Which sex of mice has a longer anogenital distance?

1. Male

2. Female

3. Both sexes are the same

4. It varies with age

The correct answer is: Male

The longer anogenital distance in male mice is a well-documented phenomenon and serves as an important morphological indicator of sex in rodents. This distance is measured from the anus to the genitalia and is typically greater in males due to hormonal influences during development, particularly androgens. The presence of these hormones promotes the growth and differentiation of male reproductive structures, which contributes to the increased distance observed in male mice compared to females. Understanding this anatomical difference is critical for researchers and technicians when identifying the sex of mice in laboratory settings. In contrast, female mice have a shorter anogenital distance, which is influenced by different developmental processes. The same measurements in both sexes would not account for the distinct sexual dimorphism observed in these animals, while variations with age are less relevant since the anogenital distance is generally established early in life and remains stable once the mice reach maturity. Thus, the distinction in anogenital distance serves as a reliable method for sex determination in mice.