ABSTRACT
The development of the ureters, bladder, and urethra starts at the caudal end of the embryo at the cloacal membrane and within the adjacent mesenchyme. Via differential growth rates of the adjacent mesenchyme, the distal primitive hindgut begins to form a dilated chamber known as the cloaca. To appreciate the development of the lower urinary tract and
female perineum, one must understand the transition from the 4 mm (4-week) to the 36 mm (10-week) embryo as the cloaca is partitioned into anterior (urogenital) and posterior (rectal) components.
