Page 9 - De-Extinction: The Science of Bringing Lost Species Back to Life

Captive breeding programs have already used the tissue
to help pull animals back from the brink of extinction.
For instance, conservationists have used sperm from the
Frozen Zoo to artificially inseminate giant pandas and other
endangered species.

RHINO RESCUE

At zoos and wildlife parks, scientists use several techniques
to breed endangered animals. The most basic is to put male
and female animals together and encourage them to mate.
Artificial insemination is another method. Neither approach
is possible with the northern white rhino. None of the three
remaining northern white rhinos, which live in a conservation
park in Kenya, can breed naturally. Sudan, a forty-two-year-
old male, has a low sperm count. His twenty-six-year-old
daughter, Najin, has injuries that prevent her from mating or
carrying a pregnancy to term. Her fifteen-year-old daughter,
Fatu, has a uterine disorder that prevents her from sustaining a
pregnancy.
Another option is in vitro fertilization (IVF). In this
process, researchers extract eggs from females, fertilize them
in the lab with sperm taken from males, and implant the
embryos that result into the wombs of females. In 2016 a team
led by San Diego Zoo Global in California and the Leibniz
Institute for Zoo and Wildlife Research in Berlin, Germany,
unveiled a plan to save the northern white rhinos using IVF.
The scientists are collecting eggs from Najin and Fatu, the last
two living females of the species, and fertilizing them with
frozen sperm. They will implant the embryos they hope will
result in a surrogate animal, the closely related southern white
rhino (Ceratotherium simum simum).

THE FROZEN ZOO 93