Definition: Any of a class of physiologically active substances present in many tissues, with effects such as vasodilation, vasoconstriction, stimulation of intestinal or bronchial smooth muscle, uterine stimulation, and antagonism to hormones influencing lipid metabolism. Prostaglandins are prostanoic acids with side chains of varying degrees of unsaturation and varying degrees of oxidation. Often abbreviated PGA, PGB, PGC, PGD, etc. with numeric subscripts, according to structure.
[fr. genital fluids and accessory glands where discovered]