Note a small adrenal gland anterior to each kidney. This is an endocrine gland and is not part of the excretory system. The kidneys have a duct or tube, the ureters leading from them. The kidneys are bean shaped and are metanephric type kidneys. The notch or hilus of the kidney is the site of entrance and exit of the vessels and the ureters.
Excretory products pass into the pelvis, thence to the ureter.
The ureters pass posteriorly and enter the neck of the urinary bladder. The urinary bladder is a pear-shaped sac supported by ligaments, with a narrowing neck which terminates in a tube, the urethra which opens to the outside. The bladder is first found in amphibians as a pocket in the floor of the cloaca. In mammals it comes from the stalk of the allantois and is endodermal in origin. It is therefore essential that you do not destroy any of the reproductive features.