USMLE Step 1 Practice Test 11

10 free USMLE Step 1 practice questions in the real exam format, covering the official content areas, with an explanation for every answer.

USMLE Step 1 Practice Test 11Tutor mode

Question 1 of 10

Reproductive & Endocrine Systems

A 16-year-old girl is brought to the physician because she has never had a menstrual period. Breast development began at the age of 11 years. She is 172 cm (5 ft 8 in) tall. Examination shows Tanner stage 5 breasts with sparse pubic and axillary hair. There is a firm, mobile mass in each inguinal canal. Pelvic examination shows a short, blind-ending vagina; no cervix is seen. Karyotype is 46,XY. Serum testosterone concentration is in the upper part of the reference range for adult men. A schematic of the urogenital ducts at the indifferent stage of development is shown. Which of the labeled structures regressed during this patient's development because of a secretory product of fetal Sertoli cells?

Indifferent-stage urogenital ducts (frontal view)

Schematic of the sexually undifferentiated genital ducts at about 7 weeks of development. Both sides are drawn; labels mark the left side and midline. Dashed lines and solid lines represent the two paired duct systems. Figure not drawn to scale.