The urachus forms from the distal end of the allantois in the embryo, and develops into a closed cord between the base of the bladder, and the navel.

[2] The fibrous remnant lies in the space of Retzius, between the transverse fascia anteriorly and the peritoneum posteriorly.

This canal is initially open, but later closes as the urachus goes on to definitively form the median umbilical ligament.

Rarely, urachus carcinomas can metastasise to other regions of the body, including pelvic bones and the lung.

[8] This article incorporates text in the public domain from page 1213 of the 20th edition of Gray's Anatomy (1918)