Strictly speaking, you cannot donate your body directly to science. But you can donate it to a number of accredited institutions who may find a number of uses for it, although the process of doing so – and what actually happens after your death – can be a bit confusing.
In the US, the process is not strictly regulated and somewhat controversial. The American Association of Tissue Banks (AATB) provide accreditation for organizations that wish to accept body donations, as does the International Institute for the Advancement of Medicine, but there is no legal obligation to do so, leading to some questionable tactics by so-called “body brokers”.
A Reuters investigation last year found that just 10 states in the US regulate body brokers, and only a handful are closely inspected. Your property rights to your body cease at death, meaning it may be used for a number of things that you did not envisage.
In the UK, the process is a bit more stringent. It’s regulated by the Human Tissue Authority, who have a list of 19 licensed medical institutions that you can contact to make arrangements for donating your body. Under the Human Tissue Act of 2004, it is illegal to sell body parts in the UK, which is not necessarily the case in the US. Again, you’ll need to fill out the proper paperwork to make the necessary arrangements after your death.

"Donated bodies, brains and tissue are invaluable resources for training or for research," Chris Birkett, the Director of Regulation at the HTA, told IFLScience. "Their bodies will be used to teach healthcare professionals and students about the human body."
There are a number of conditions that must be fulfilled in order for your body donation to be accepted. You must have no history of communicable diseases and you must also be in generally good health prior to your death. If an autopsy is required, medical institutions will usually refuse to take your body afterward.
What happens after is a bit more complicated. There are strict guidelines from the HTA that must be adhered to following your death, including proper ethical treatment of your cadaver. Some institutions may even carry out a memorial service.
If your body is accepted, it may be embalmed by a medical institution following your death, which means preserving fluid is injected to disinfect your body and prepare it for dissection. After this, your body is stored in a refrigerator for use at a later date, which could be months later. A preserved body can last for up to 10 years.
Bodies that have been embalmed can be used by students for dissection. They may take months to remove your skin and probe your muscles, nerves, and organs. When the research is complete, the remains are gathered together and cremated.
There are a lot of other things your body can be used for. Some are used as crash test dummies, with X-rays and autopsies being used to examine any damage to the cadaver. In the US, some bodies are used for forensic research at a body farm run by the University of Tennessee. Others may even go on display in exhibitions, either in full or in part.
In the UK, you can specify which institution you would like to take your body after your death. Bodies listed as being for anatomical education can then be used by medical students for dissection and other research, such as looking into specific diseases. Aside from registering with the HTA, you can also put this in your last will and testament to donate your body.

"We take bodies in for anatomical education, part of medical education if you like," Dr Peter Bazir from Hull York Medical School (HYMS), one of the 19 institutes licensed by the HTA in the UK, told IFLScience. "So we get donated bodies that come in, and we embalm them in preparation for use by our students or doctors."
Dr Bazira added that bodies that have been embalmed can typically be used for up to three years, unless more stringent time restrictions have been put in place by the donor. After this, the body is normally cremated.
Sadly in the US, the process is a lot less regulated. Some bodies are rented out multiple times to different institutions. You can designate a specific disease you would like your body to be used for research on, but there is no guarantee that will happen owing to difficulties with differing demands for cadavers.
Quartz noted that a former dentist in Oregon had been able to buy a refrigerator full of human heads for his own experiments. In Honolulu in 2011 and 2012, a man was repeatedly found to be in possession of human remains, but could not be prosecuted as no state law applied.
Unfortunately, if you’ve got a specific vision in mind for your body after you die, then in the US at least that may not be fulfilled. Becoming an organ donor might be more tempting, with your body then possibly being used to save somebody else’s life.
There are still official avenues to go down, and body donation is extremely useful in medical research. But you might want do be careful that it doesn't end up in unwanted hands, and ensure that you go down formal accredited routes if you do decide to donate it after your death.