Prostaglandins (PGE, Prepidil Gel) are a group of lipids made at sites of tissue damage or infection that are involved in dealing with injury and illness. They control processes such as inflammation, blood flow, the formation of blood clots, and the induction of labor in humans. They are given in female poultry to help induce oviductal contractions. However, this drug should only be administered by a veterinarian who should do so with extreme caution. This is because it can potentially cause the egg to rupture while inside the bird s reproductive tract. When applied as a topical gel, it is less risky. There are four principal bioactive prostaglandins: prostaglandin (PG) E2 (PGE2), prostaglandin (PGI2) (this is also known as prostacyclin), prostaglandin D2 (PGD2) and prostaglandin F2α (PGF2α). Prostaglandins are made at sites of tissue damage or infection, where they cause inflammation, pain and fever as part of the healing process. When a blood vessel is injured, a prostaglandin called thromboxane stimulates the formation of a blood clot to try to heal the damage; it also causes the muscle in the blood vessel wall to contract (causing the blood vessel to narrow) to try to prevent blood loss.