PAX8 has been detected in embryonic structures associated with the female reproductive tract. Which structure is it?

• A. Urogenital sinus
• B. Mullerian ducts
• C. Wolfian ducts
• D. Mullerian eminence

Answer: (B)

PAX8 marks tissues from the Müllerian (paramesonephric) ducts, which in the female embryo develop into the main structures of the female reproductive tract—the fallopian tubes, uterus, and the upper part of the vagina. Detecting PAX8 in embryonic structures points to the Müllerian ducts as the source. The urogenital sinus contributes to lower parts of the vagina and urinary structures, the Wolfian (mesonephric) ducts are the male precursor and largely regress in females, and the Müllerian eminence is a transient structure not forming the main female tract. So the structure associated with the female reproductive system where PAX8 is detected is the Müllerian ducts.