It absorbs the ends of the mesonephric ducts and the associated ends of the renal diverticula, and these give rise to the trigone of urinary bladder and part of the prostatic urethra. Mesoderm extends to the midventral line for some distance behind the umbilical cord, and forms the lower part of the abdominal wall; it ends below in a prominent swelling, the cloacal tubercle, which after the separation of the rectum becomes the genital tubercle. After the separation of the rectum from the dorsal part of the cloaca, the ventral part of the cloacal membrane becomes the urogenital membrane. Rather, the urogenital part of the cloacal membrane separates the ingrowing sheets of mesoderm. The ureter opens at first into the hind-end of the Wolffian duct; after the sixth week it separates from the Wolffian duct, and opens independently into the part of the cloaca which ultimately becomes the urinary bladder. The median lobe of the prostate is formed as an extension of the lateral lobes between the common ejaculatory ducts and the bladder. In the male, the duct persists, and forms the tube of the epididymis, the vas deferens and the ejaculatory duct, while the seminal vesicle arises during the third month as a lateral diverticulum from its hinder end.