The term prostaglandins refers to a family of C20 cyclopentane fatty acids found widely distributed in mammalian tissues and possessing a variety of biologic activities. Fourteen naturally occurring prostaglandins have been isolated and numerous synthetic ones prepared. They are designated as prostaglandins E, F, A, or B (PGE, PGF, PGA, PGB) on the basis of structural differences on the cyclopentane ring, and further subdivided by numerical subscripts according to the degree of unsaturation of their side chains.
Human seminal fluid was first shown to contain these substances when its ability to induce muscular activity in isolated myometrium was investigated.1 Since then the prostaglandins have been found in human seminal vesicles (not prostate as was originally thought), lung, and menstrual fluid, and in thyroid carcinomata.2,3 Central nervous system tissue, intestines, spleen, kidney, and adrenal gland from other mammals have been found to be sources of prostaglandins. It has been