The spasmogenic effect of 11 biogenic polypeptides, 2 prostaglandins and 3 amines was assayed, in parallel, on the isolated seminal vesicles and deferent ducts of the rat, guinea pig and hamster. The smooth muscle preparations were contracted by most of the examined compounds, but none of the preparations appeared to be particularly sensitive, and not infrequently bioassay was made difficult by tachyphylaxis. Thus, the smooth muscle preparations of the male genital tract, although containing receptors for biogenic polypeptides and amines, cannot be considered as test objects of first choice in the qualitative and quantitative bioassay of these compounds
