SAN DIEGO (CBSLA/CBS News) – For the second time this year, a southern white rhino at the San Diego Zoo Safari Park has been impregnated via artificial insemination as researchers look for ways to resurrect the nearly extinct northern white rhino, of which only two are left in the world.

Amani. (San Diego Zoo)

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The San Diego Zoo announced Tuesday that 10-year-old Amani was impregnated through an artificial insemination that took place in July with sperm from a male named J Gregory.

This comes after the zoo reported in May that Victoria, another of the six female southern white rhinos that live at its Nikita Kahn Rhino Rescue Center, had also become pregnant by artificial insemination.

Rhino gestation can take up to 18 months, and the two calves will likely be born in late 2019.

“Many months of intensive animal training, reproductive research and veterinary care resulted in these two ongoing pregnancies from artificial insemination,” said Dr. Barbara Durrant, director of reproductive sciences for the San Diego Zoo, in a statement. “We are following Victoria and Amani closely, continuing to gather critical information about early fetal development and the endocrinology of rhino pregnancy.”

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Victoria. (CBS News)

According to the International Rhino Foundation, there are only 29,500 rhinos worldwide. In 2017, African poachers killed more than 1,100. Three of the world’s five rhino species could be lost in our lifetime, the IRF says.

The southern white is one of two subspecies of white rhino. Researchers are hoping to use artificial insemination to resurrect the other subspecies, the northern white, of which only two exist in the world: a mother and daughter in Kenya who are under 24-hour armed guard.

To do so, according to the zoo, scientists must sequence the northern white rhino’s genome. They must then use northern white rhino cells which are in the Safari Park’s Frozen Zoo — the largest gene bank in the world – to stem cells and create sperm and eggs.

“So we have cell lines from 12 different northern white rhinos. And that is enough genetic diversity to bring back a self-sustaining population of northern white rhinos,” Durrant told CBS News last month.

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Durrant believes assisted reproduction and stem cell research gives scientists an opportunity to resurrect the northern whites. A team from the Leibniz Institute in Berlin has been perfecting a procedure to harvest rhino eggs, and hopes to extract eggs from the remaining two northern white females this year.