Edinburgh Zoo pandas: Put in same enclosure to mate
The giant pandas at Edinburgh Zoo have been brought together to mate five times but so far have been unsuccessful.
Yang Guang was allowed into Tian Tian's indoor cage through a grate for five minutes at a time.
The 20st (127kg) male bear was showing more aggression, which the zoo said was a good thing.
Female pandas ovulate just once a year, with a narrow window of just 36 hours in which they can get pregnant.
The couple will be brought together again on Wednesday.
A Chinese panda expert, who checked on the female Tian Tian at 09:00, judged that she was ready.
The pandas have been taken off display, and the online "pandacam" has been switched off, while a team of zoo keepers observe to see if they mate.
Zoo staff said Tian Tian's tail kept getting in the way. Keepers have using a long poll to try to raise the female panda's tail.
The two pandas, who arrived at Edinburgh Zoo from China in December, have been kept in separate enclosures.
Tian Tian ovulated during the night, which led zoo officials to open the gate between the two cages.
An Edinburgh Zoo spokeswoman told the BBC Scotland news website: "The urine samples we took on Monday morning came back at 21:00 on Monday with results saying Tian Tian had not ovulated.
"However, our Chinese panda expert checked her on Tuesday morning and he said she had ovulated in the night and because our tests take about 12 hours to get back to us we could not wait so the pandas have been put together."
She added: "When they were put together they wrestled a lot, but in a good way.
"Before the grate went up Tian Tian was making high pitched calls and their paws were up against the grate.
"Her body language was also very encouraging. Yang Guang has responded promisingly each time."
Panda pregnancies can last for anything between 85 and 100 days.
The zoo has confirmed they will not use artificial insemination if the pandas fail to mate successfully this year.