Helping rare species strut their stuff.

Countries where gorillas live in the wild stopped exporting the endangered animals to zoos in the United States in 1976. And some captive gorillas produce few or no offspring. As a result, the gorilla gene pool in the United States has become limited.

To increase genetic diversity in this population, researchers are turning to in vitro fertilization techniques developed for humans. In December, a lowland gorilla at the Cincinnati Zoo and Botanical Garden is expected to give birth to the first test-tube gorilla--and the first test-tube endangered primate--says zoo scientist Betsy L. Dresser. A gorilla at an Omaha zoo provided the sperm.

In vitro techniques enable researchers to take sperm and eggs from distant animals and create embryos that they can implant in a female or freeze for later use, Dresser explains.

Zoo scientists may one day import sperm from wild gorillas for use in captive creatures, she says, or even export zoo-grown embryos for implantation in wild animals.

In Kenya, zoo researchers have implanted embryos from bongos, a rare antelope, into the more common eland. The surrogates care for the babies as if they were their own flesh and blood, although elands don't share bongos' chestnut brown coloring, says Dresser. Eventually, researchers would like to use lowland gorillas as surrogate mothers for Rwanda's rare mountain gorillas. No mountain gorillas exist in captivity.

Scientists have experimented with in vitro fertilization in cats, baboons, and rhesus monkeys. Antelopes are the only other endangered species to have had a test-tube baby, she says.