What term describes the distance between the genitals and the anus, used to determine sex in mice and rats?

• A. Anogenital distance
• B. Genital-rectal distance
• C. Caudo-ventral length
• D. Postnatal measurement

Answer: (A)

Anogenital distance is the distance between the anus and the genitalia. In mice and rats, this measurement is sexually dimorphic because prenatal androgen exposure drives longer distances in males than in females, making AGD a reliable way to determine sex in newborns. It’s also used as a sensitive marker for endocrine disruption in developmental studies. Measurements are typically taken with calipers from the center of the anus to the base of the genital tubercle or genital opening, with some protocols distinguishing slightly different landmark definitions (AGD variants) depending on the exact method. The other terms aren’t standard names for this specific anatomical distance.