My father, Donald, has been terminally ill with a bone marrow cancer for more than four years - his once enormous frame is now ravaged - I couldn't imagine that science would have much use for him.

In fact, I wasn't at all sure that science still needed bodies. No-one ever seemed to talk about a shortage. Hadn't computers replaced the role of the cadaver?

But Dad was adamant. "A dead body is a very unattractive thing. You won't want mine hanging around, and I can't stand funerals. Surely a medical school will take me?" A couple of forms, a witness signature and a week later he got the answer he was hoping for. The University of Dundee, Life Sciences College accepted his "generous offer". He was grinning from ear to ear.

Dependent on two pints of donated blood every fortnight and debilitated by an enlarged spleen, Dad has felt physically useless for years - now in death his body would serve a purpose.

"And it won't cost a penny. I've just got to make sure I don't die between Christmas and January 5. The university doesn't do collections then - especially not somewhere as remote as Rannoch!"

Dad is determined to see out the festive period - he is particularly proud of his newly planned, credit-crunch-proof demise.

That his body will be put to good use is a real bonus. Apparently, the need for such bequests has never been greater. While organ donations have risen in recent years, the reverse is true for bodies: in Scotland demand increasingly outstrips supply, while England and Wales have seen a year on year fall in donors since 2000.

"They are our silent teachers," explained Sue Black, professor of anatomy at Dundee University. "The training of future doctors depends on these donations but having sufficient bodies cannot be taken for granted."

Anatomy departments have a PR problem. More than 150 years on and the legacy of the body snatchers still looms large. There remains a tendency to associate the dissection of cadavers with a morally murky, bygone era.

In the 19th century only the criminal dead could be given to science. This left the rapidly expanding medical world with a huge shortfall and the system was open to horrendous abuse. In the wake of murderous Burke and Hare the law changed but it wasn't until the first half of the twentieth century that a shift in attitudes brought about an increase in general donations.

Two world wars saw patriotism swell and the nation did whatever it could to help the doctors on the front line. But by the late 1940-50s the country was in the grip of a chemotherapeutic revolution - there was a belief that modern medicine could solve everything - and body donations peaked.

Subsequently, a more sceptical media and scandals such as Alder Hey and the Bristol heart babies have made the public wary. People confuse pathology with anatomy and don't realise the latter is there solely for educating future doctors.

Bodies are desperately needed for this teaching process but medics don't feel comfortable asking for such a deeply personal gift.

In Britain we are all too good at pushing the prospect of death and its aftermath under the carpet. My father has been sick for years but people still get embarrassed when I mention life after he's gone - euphemisms abound and friends talk of him "getting better".

Dad is a realist, however. Years of working with livestock has taught him that death is inevitable and a carcass is no more than an empty shell. Why not donate what's left to learning instead? Of course, not every potential donor is likely to be as cavalier about the idea of their dead body. However, as my father and anatomists are at pains to point out, the deceased are treated with the utmost respect and dignity.

"Bodies are embalmed within 48 hours and all of us - mortuary technicians, students and teachers - treat the donors as if they are our own kith and kin," explained Professor Vishy Mahadevan from the Royal College of Surgeons of England.

But in 2002 Channel 4's Autopsy Live undid much of the good work - overnight, donations plummeted. A dead body as the subject of attention-seeking television was hardly a recipe in taste and decency. Potential donors lost confidence and, through no fault of their own, medical schools were left with a shortfall. Despite Scotland's unrivalled reputation as a centre of anatomical learning, only three of its universities still offer students the opportunity to dissect a human body.

"It is essential to be able to work with the deceased," explained Professor Black, using the example of my father to outline her point. His condition, myelofibrosis, has left him with an enlarged spleen. Access to his body will allow trainee doctors to see the extent of the spleen's distortion, the altered position of the stomach and the effect on blood supply. Students will acquire an understanding of how this cancer disables and what might be done to ease the discomfort.

Increasingly sophisticated medical procedures demand an ever more involved understanding of the human body. Professor Mahadevan took keyhole surgery as a case in point. "When you lift the bonnet of a car you can see how to mend it, but if you can only drill a small hole in the bonnet your knowledge of what is happening underneath needs to be more extensive and the same applies to the human body. The intricacies of endoscopic surgery mean our knowledge needs to be greater."

The 2006 amendment to the Anatomy Act has also greatly increased the need for donors; under the law, surgical procedures can now be practised on the deceased. This legal change has been particularly important in orthopaedics - for example, when replicating hip replacement surgery students can now practice exchanging the original thigh bone in a donor's body with a prosthesis before facing an equivalent scenario in live theatre. The only real obstacle left to future learning is an anticipated lack of donations.

However, the emotional need to have a coffin at a funeral will remain an obstacle for many potential donors' families and for a bequest to become a donation it's essential the family are behind the decision.

Dad was fortunate - Mum is philosophical about his plan to donate. Nonetheless, it was a comfort to hear all donors are cremated or buried within three years. Each university holds its own memorial service for the relatives of the deceased and every year teachers and medical students turn out to pay their respects.

Angus Arthur, whose mother Hilda donated her body to Dundee University in 2005, found the service and the return of his mother's ashes important. "I was able to scatter her ashes on the banks of the River Tay, where we installed a bench to remember her."

Hilda was a district nurse and wanted to support the NHS, and Angus admitted that as a family they had felt burial and cremation had become too commercial.

For Professor Black, body donation is "an incredibly generous, selfless act". I confided in her that my father was attracted to the idea partly because he wouldn't have to pay for a burial. "That's OK," she laughed. "My favourite story is when a man of 80 came to see me and said - I can't tell you how good it is to hear a woman such as yourself wanting an old body like mine!'"

Professor Black carries a donor card but, at 60, organ donation becomes less likely and when she reaches that age, she, too, will arrange to guarantee her body is used for anatomical instruction.

Back in Rannoch, having discovered how essential donations are, my father is more determined than ever to survive the festive period.

For those interested in registering as body donors there are Bequethal Administrators at each of Scotland's five medical school anatomy departments. Future donors should make arrangements with their nearest - Dundee, St Andrews, Glasgow, Edinburgh or Aberdeen.