In order to understand bladder cancer, one must first have some basic knowledge of the normal bladder.
The bladder is a hollow organ with muscular walls. Its main function is to store urine. The average adult bladder holds about 2 to 3 cups of urine. Urine is made by the kidneys and then drips down to the bladder through tubes called ureters. During urination, the bladder muscle contracts, and urine travels out through a tube called the urethra. In women, the urethra is a very short tube that opens just above the vagina. In men, the urethra is longer. It passes through the prostate gland and the penis, and opens at the tip of the penis.
Layers of the Bladder Wall:
Mucosa: This is the inner-most layer of cells directly in touch with the urine. These cells are called urotherlium or transitional cells. This layer of cells covers most of the urinary tract: urthera, bladder, ureter, and the collecting system of the kidney.
Lamina Propria: Beneath the urothelium is a thin layer of connective tissue called the lamina propria.
Muscularis Propria: Next is a layer of muscle tissue called the muscularis propria. This is the muscle layer of the bladder responsible for contraction of the bladder to push urine out during voiding.
Fatty Layer: Beyond the muscle, another zone of fatty connective tissue separates the bladder from nearby organs.