The Molecular Pathogenesis of Bladder Cancer

textabstractThe bladder is a hollow organ in the small pelvis. It stores urine that is produced when the kidneys filter the blood. Four different layers, the epithelium, lamina propria, muscularis, and connective tissue, define the bladder wall. The epithelium consists of 7 to 10 cell layers and rests on a basal lamina synthesized by epithelial and mesenchymal cells (Figure 1). The thickness of the epithelial cell layer and the lamina propria depends on the degree of distension of the bladder. The cells of the epithelium are referred to as transitional cells. They line the urinary tract starting at the kidney, down the ureter, into the bladder and most of the urethra. Their shape varies between cubical and flat. The latter cells form the barrier between urine and the epithelium. Because of their large fiat morphology these superficial cells are sometimes named umbrella cells. The muscle coat of the bladder is also referred to as the detrusor muscle. It allows the bladder to get larger and smaller as urine is stored or emptied