During the 1980s and '90s, it was all the rage for some Hong Kong celebrities and tai-tais to disappear from public view and re-emerge a few weeks later looking much younger.
And the key to this magical makeover? Sheep - or more precisely lambs residing in the Swiss Alps.
Wealthy Hongkongers were checking into beauty resorts in the country and receiving anti-ageing injections extracted from sheep organs, usually the placenta or liver.
Nowadays, this unconventional and expensive form of live cell therapy, which often costs a quarter of a million Hong Kong dollars per treatment, is less popular in Hong Kong amid an avalanche of cheaper products and treatments.
But over the past five years, a growing number of mainlanders have been travelling to Switzerland to try the alternative therapy, either through injection, oral medication, or a combination of both.
Montreux, a picturesque town near Geneva with a concentration of cell therapy clinics, has seen a notable rise recently in mainland medical tourists. Over the last five years, demand by mainlanders has increased substantially,' says Dr Adrian Heini, medical director of Clinique La Prairie, a luxury spa located in the Swiss town.
The surge in demand has caused many mainland travel agencies to launch 'sheep placenta therapy tours' to Montreux. Shanghai Hongyan Bio-technology, for example, recently launched a nationwide campaign to promote its medical tourism packages. They charge from 328,000 yuan (HK$400,259) for eight injections over eight days, to 688,000 yuan for 16 injections over 10 days. Airfare and accommodation are included.
There is no shortage of anti-ageing products or therapies available on the mainland. But those who can afford it believe flying to Switzerland for a few jabs believe the money and hassle are worth it.
'Sheep placenta cell injection was developed in the West nearly 90 years ago, but the mainland's anti-ageing technology has only been around for 10 to 20 years,' says Damy Yantao Zhou, general manager of Shanghai Hongyan.
'The safety and development level [in China] cannot compare with Switzerland's sheep placenta treatment. This is the main reason why people prefer going there,' says Zhou.
But despite its rising popularity, live cell therapy is still an unfamiliar concept in the mainland, says Zhou, and few people are aware of its benefits. These are said to include the rejuvenation of cells, the boosting of immunity and energy levels, as well as an increased libido. The effects are said to last for a couple of years.
'Many have heard of it but have no idea what the treatment involves,' Zhou says. 'We are talking about a middle-class market with 20 million people. The number of people who have tried the treatment is relatively small.'
To appeal to customers, some operators lean on the celebrity factor. For example, Shanghai Hongyan claims that renowned figures such as Winston Churchill, Princess Diana and Nelson Mandela all received sheep placenta therapy.
Swiss Medical Tourism, another mainland tour operator, splashes pictures of Churchill, Marilyn Monroe and Argentine football legend Diego Maradona on its website's homepage.
Asked whether there is any proof that these public figures have ever undergone treatment, Shanghai Hongyan customer service officer Echo Tang says: 'Nelson Mandela looked very emaciated when he got out of jail and it was sheep placenta injections that revitalised him.'
Tang says that 60 per cent of customers are men. 'Many of them are company CEOs,' she says. 'Their age range is 40 to 60 - the same as female customers.'
The future of the market looks rosy, but some operators have expressed misgivings.
Kenneth Tang, a Hong Kong-based spokesman for GoEuGo, a travel company headquartered in the Netherlands, says there are some mainland operators which are trying to lure customers with cheaper options that sacrifice quality.
'They offer shorter trips so you can get a few jabs over a shorter period of time,' Tang says.
'These appeal to mainland travellers who don't want to spend days cooped up in the clinic unable to go shopping.'
These treatments may not be as effective, as doctors do not have enough time to see how the body reacts to each injection. 'The last thing we want is for such operators to give their clients an unsatisfactory experience,' Tang says.
But Tang is hopeful for the industry: 'In the mainland market, consumers like to do what other people do. As more people do it, others will follow suit.'