Ultrasound image shows the growing rhino embryo. Courtesy San Diego Zoo

Researchers at the San Diego Zoo announced Thursday they have confirmed a pregnancy from artificial insemination in one of the southern white rhinos living at the Nikita Khan Rhino Rescue Center.

The pregnancy, created with sperm from a male southern white rhino, is an important milestone in the ongoing work to develop the scientific knowledge required to genetically recover the northern white rhino, a nearly extinct subspecies. Only two northern white rhinos remain on Earth, and unfortunately both are female.

“The confirmation of this pregnancy through artificial insemination represents an historic event for our organization but also a critical step in our effort to save the northern white rhino ,” said Barbara Durrant, director of reproductive sciences at the zoo’s Institute for Conservation Research. “The sperm had excellent motility and the procedure went very well — we are excited to confirm a pregnancy has occurred but we have a long time before we can declare a real success with the birth of a healthy southern white rhino baby.”

Rhino gestation lasts from 16-18 months. The artificial insemination of a rhino named Victoria occurred on March 22 at the San Diego Zoo Safari Park. If Victoria is able to carry the calf to term, it could arrive in the summer of 2019.

A key element of the program at the Rhino Rescue Center is the ability of animal care staff to work closely with the rhinos, building positive relationships so the animals participate voluntarily in procedures like artificial insemination and ongoing monitoring of pregnancies.

“Just the fact that we have been able to confirm this pregnancy while the embryo is just a few weeks old is tremendously important and is all due to the work that animal care staff have put into developing relationships with these rhinos,” said Parker Pennington, a post-doctoral associate. “Through regular cooperative ultrasounds with Victoria we will be gathering a lot of data about the progress of a rhino pregnancy.”

To reach the ultimate goal of successfully producing a northern white rhino, multiple steps must be accomplished. One of the first steps involves sequencing the genome of the northern white rhino to clarify the extent of genetic divergence from its closest relative, the southern white rhino. Another step requires conversion of cells preserved from 12 individual northern white rhinos to stem cells that could develop into sperm and eggs—a process successfully begun in the laboratory of Jeanne Loring of The Scripps Research Institute.

Reproductive options include artificial insemination, in vitro fertilization and embryo transfer, with the southern white rhinos possibly serving as surrogates for northern white rhino embryos.

There are many challenges ahead, but San Diego Zoo researchers are optimistic that a northern white rhino calf could be born from these processes within 10 to 15 years. This work also may be applied to other rhino species, including critically endangered Sumatran and Javan rhinos.

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