Which of the following structures does the fetal allantoic duct become in the adult?: (A) Cloaca, (B) Medial umbilical ligament, (C) Urachus, (D) Ureter
Answer is C. Urachus The urachus is a fibrous remnant of the allantois, a canal that drains the urinary bladder of the fetus that joins and runs within the umbilical cord. The fibrous remnant lies in the space of Retzius, between the transversalis fascia anteriorly and the peritoneum posteriorly.