II. The Uretero-Vesical Valve

Abstract

The uretero-vesical orifices were studied in the excised bladders of human, pig, dog, cat, rabbit and monkey. The intra-vesical ureter was found to serve as a true valve. It is not a sphincter dependent upon muscle tone or muscle contraction, but acts passively. Cutting away the uretero-vesical valve (intra-vesical ureter) was found to permit reflux of fluid from the bladder into the ureter in all bladders tested, except in one human bladder with very thick wall. In urinary bladders in which the valves were normal (not sclerosed, edematous, partly destroyed or inflamed) regurgitation did not occur in man, cat, dog, pig and monkey, unless the injection pressures were excessive and the volume of fluid injected exceeded that found normally in the bladder. Stretching the bladder mucosa by injecting into the bladder excessively large amounts of fluid under high pressure shortened the valves and in many instances rendered them incompetent. Contraction of Bell''s muscle simultaneously pulls the uretero-vesical valve toward the urethra and opens the internal urethral sphincter.