The Acpo audit was sparked following a series of inspections by the Human Tissue Authority in 2009, asking for details of category three human tissue - significant body parts including organs and limbs - held by police before the Human Tissue Act came into force in 2006.

BBC: Further body parts kept by Avon and Somerset Police

Vitamin D receptors are present in nearly every tissue in the human body.

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In the U.S., some universities and corporate laboratories are conducting research on "bioprinting, " or artificial construction of body parts using living human tissue.

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It also kept 126 samples registered as category two, which are defined as "samples of human tissue which are not a significant part of the body - for example small tissue samples, blocks, slides, etc".

BBC: Further body parts kept by Avon and Somerset Police

It also was conducted in a lab and so cannot account for the protection a human body might offer, such as layers of skin, bone and tissue.

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