A report says that thousands of brains may have been taken during post mortems without the knowledge or consent of relatives.
The government says it intends to tighten the law surrounding these issues.
Why was there an investigation?
The inquiry - ordered by ministers - followed a campaign by Elaine Isaacs, from Manchester.
Her husband, Cyril, committed suicide in 1987 after suffering from depression.
Elaine later discovered by accident that his brain had been removed following a post mortem for research purposes.
Elaine is an observing Jew, and would have had strong religious objections to such an act.
What did the inquiry find?
The inquiry looked both at common practice in the Manchester area, and nationwide.
It found further evidence that much brain tissue had been taken without the consent of relatives.
A questionnaire sent out to hospitals across the country revealed that at least 21,000 brains had been "collected" between 1970 and 1999.
The majority of these had been taken in the wake of "coroner's cases".
While there was no firm evidence of exactly how many had been taken without consent, the inquiry suggested that there was a widespread culture during much of this period which assumed that taking the tissues in this way was ethically acceptable.
It may never be known whether proper consent was taken in the bulk of these cases.
What does the law say?
The Human Tissues Act 1961 does say that tissues from Coroner's post mortems should not be used if relatives object.
This means that, taking tissues in the assumption that relatives did not object would be against the law.
The inquiry found that while some research teams were "scrupulous" in observing these requirements, there had been widespread failure to do so elsewhere.
What will now happen to the law?
The government has pledged to reform the law in the wake of the latest report, and the inquiry findings which followed the Alder Hey scandal.
It intends to "enshrine the principles" of informed consent - changing the emphasis away from simply acting if relatives object, towards having to gain explicit consent in every case.
The Human Tissue Act is to be strengthened to incorporate this change.
The Retained Organs Commission was set up in the wake of Alder Hey to oversee a public consultation on this.
There are also likely to be changes to doctors' disciplinary codes and the rules relating to coroners.
Why are some medical experts worried about the impact on research?
Brains given to research are a vital component in the search for cures and treatments for a variety of brain diseases that seriously affect the lives of thousands.
Experts point out that drugs for Alzheimer's and Parkinson's patients would never have been developed if it were not for brains taken at post-mortem.
They are hopeful that close examination of brains will yield further clues to schizophrenia and depression, among others.
However, there is widespread concern that outcry over this issue could lead to far fewer organs being made available, as members of the public become far less willing to allow their relatives organs to be used.
Brain tissue, in many cases, is now imported into the UK for use in research.