Assistant Laboratory Animal Technician (ALAT) Practice Exam

Which sex of mice has a shorter anogenital distance?

1. Male

2. Female

3. Both sexes are the same

4. It varies with age

The correct answer is: Female

In mice, the anogenital distance, which is the measurement from the anus to the genital opening, is typically shorter in females compared to males. This distance is a sexually dimorphic trait, meaning it varies between the sexes and is used in distinguishing male and female mice, particularly in younger individuals where external genitalia may not be fully developed. The physiological differences between male and female mice are linked to their reproductive anatomy and functions. Males usually exhibit a longer anogenital distance as a result of their reproductive anatomy, which includes the positioning of the testes. Understanding these differences is crucial in laboratory settings, especially for breeding, housing, and experimental design, as it's important to correctly identify the sex of the animals being studied or bred. This knowledge enables researchers to control for variables that could influence experimental outcomes or breeding successes.