Nerve fibers in tumors of the human urinary bladder.

Abstract. Exophytic tumors of the urinary bladder were examined by means of transmission electron microscopy for the presence of neural tissue because, as yet, there has been hardly any discussion of a neuronal component in the biology of neoplasms. In the stroma and rarely in the epithelium of bladder tumors, fine nerve strands were found to be irregularly distributed. These strands comprised one to a maximum of five axons containing predominantly colocalized clear and dense-core vesicles. Immunohistochemistry revealed some nerve-like structures showing vasoactive intestinal neuropeptide (VIP) reactivity. This response and the combination of vesicle types indicate that parasympathetic cholinergic neurons contribute to the innervation of the tumors. Thus, a morphological basis for neuronal influence on the behavior of such tumors has been demonstrated.