Porcine zona pellucida is a form of zona pellucida

Zona pellucida

The zona pellucida is a glycoprotein membrane surrounding the plasma membrane of an oocyte. It is a vital constitutive part of the latter, external but of essential importance to it...

 extracted from the ovaries of pig

Pig

A pig is any of the animals in the genus Sus, within the Suidae family of even-toed ungulates. Pigs include the domestic pig, its ancestor the wild boar, and several other wild relatives...

s, often referred to by the initials PZP.

The zona pellucida is a thick membrane that surrounds the unfertilized eggs of mammals. In order for an egg to be fertilized, sperm must first bind to, and then penetrate the zona pellucida. When porcine (pig) zona pellucida is injected into other mammals, antibodies are produced which attach to that animal's zona pellucida, preventing the sperm from attaching to the egg, therefore preventing fertilization.

Porcine zona pellucida has been used in wildlife contraception

Wildlife contraceptive

Wildlife contraceptives of various kinds are under development. Contraceptives such as these are intended to control population growth among both tame and wild animals....

 since the late 1980s. Animals with which PZP has been employed in this context include elephant

Elephant

Elephants are large land mammals in two extant genera of the family Elephantidae: Elephas and Loxodonta, with the third genus Mammuthus extinct...

s, feral horses

Mustang (horse)

A Mustang is a free-roaming horse of the North American west that first descended from horses brought to the Americas by the Spanish. Mustangs are often referred to as wild horses, but there is intense debate over terminology...

, elk

Red Deer

The red deer is one of the largest deer species. Depending on taxonomy, the red deer inhabits most of Europe, the Caucasus Mountains region, Asia Minor, parts of western Asia, and central Asia. It also inhabits the Atlas Mountains region between Morocco and Tunisia in northwestern Africa, being...

 and whitetailed deer

Deer

Deer are the ruminant mammals forming the family Cervidae. Species in the Cervidae family include white-tailed deer, elk, moose, red deer, reindeer, fallow deer, roe deer and chital. Male deer of all species and female reindeer grow and shed new antlers each year...

.