The Mating Game, Panda Style

By CBS News correspondent Thalia Assuras.

Here's the thing: People love giant pandas. Two visits to Washington's National Zoo this week proved that beyond a doubt. Near the panda yards, children trembled with excitement, running toward vantage points. There were excited shouts of, "Where are they?"

People also can't get enough of panda love stories. Just tell your colleagues that you're working on a piece about female Mei Xiang's latest effort at motherhood and the oohs and aahs clinch your momentary celebrity.

It is springtime and love is in the air. It's also prime time, the only time female pandas ovulate, and they do that just once. The National Zoo allowed us unprecedented access as zookeepers, vets and scientists tried to pinpoint Mei's prime propagating time. It's a lot of work over several weeks, but concentrated in the last few days with everyone on call.

The SWAT team of hormone testing — it gets samples from urine — was moved from its Virginia labs to on-site facilities. We followed them as they used a syringe to get a sample, rushed it to their hilltop lab, started tests, and then had to wait three hours to determine whether Mei's estrogen level had plummeted. That would mean the egg had been released.

Other scientists got Mei into a large cage, bribed her with food, then obtained swabs to determine if the cells in her reproductive regions had changed. That, too, would signal that special moment of liberation for the egg.

Mei, of course, was busy expressing her readiness. Usually she doesn't do all that much except eat bamboo, lounge around, and elicit squeals of joy. She can't help it. She's just too cute. But in this climate of love she paced back and forth indoors, depositing her mating scent wherever she could.

This spring represent her first chance at procreation, her only ovulation, since having cub No. 1, Tai Shan. He was born in 2005 and if you remember, he was called Butterstick before being named officially. Why? You must recall: He really looked like a butterstick and he was that tiny. Not anymore.

Papa bear was Tien Tien, Mei's playmate at the National Zoo. The two had tried mating the usual way — but when that didn't work, the reproduction folks tried artificial insemination. This time, Tien didn't even make the cut as the donor. In the panda world, his genes are quite common — not a good thing if the species is endangered. The goal is to find new blood to avoid inbreeding.

So reproductive biologist-turned-matchmaker JoGayle Howard went looking somewhere else and found the perfect specimen at the San Diego Zoo. You can call him Super Stud, but his real name is Gao Gao. Because he was captured in the wild, his genes are quite unique.

The cross-country coupling has been complicated, though. And there's been no romance: Mei hasn't even met her new man, and never will.

Gao came to her in a metal can, hand-carried by Howard all the way from California. He got to go first-class, she told us; while flight attendants put the container in a first-class closet, surrounded it with pillows and babied it all the way from San Diego to Washington, Howard went back to coach.

Finally, overnight, the deed was done. You get the picture — and today Howard declared they got the timing right. The sperm was good. Did it work? Well, it will take up to five months to find out. You see, it's notoriously difficult to tell of a panda is pregnant. Stay tuned.