Dissection (also called anatomization) is usually the process of disassembling and observing something to determine its internal structure and as an aid to discerning the function and relationships of its components. It may refer also to some spontaneous natural process of disassembly as in aortic dissection.
Vivisection refers to the dissection of a living animal, often for the purposes of physiological investigation. However, in modern parlance the term is often used to refer to any type of experimentation in which animals are injured, with or without actual dissection.
Dissection is often performed as a part of determining a cause of death in autopsy (on humans) and necropsy (on animals) and is an intrinsic part of forensic medicine, such as would be practiced by a coroner.
Later, human dissections were conducted by the Arabian physician Ibn Zuhr (Avenzoar) (1091-1161) in al-Andalus, followed by several other Arabian physicians: Saladin's physician Ibn Jumay in the 12th century, Abd-el-latif in Egypt circa 1200, and Ibn al-Nafis in Syria circa 1242.
Dissection of human cadavers for medical education has gone through periods of legalization and proscription. It was banned in much of Europe under an edict of the 1163 Council of Tours, and an early 14th century decree of Pope Boniface VIII renewed the proscription. As a result, much anatomical research and education was done covertly. Some European countries began legalizing the dissection of executed criminals for educational purposes in the late 13th and early 14th centuries, and Mondino de Liuzzi carried out the first recorded public dissection around 1315. Vesalius in the 16th century carried out numerous dissections in performing some of the most extensive anatomical investigations up to his time, but due to the continuing papal prohibition, had to carry out much of his work in secrecy, and was eventually accused of grave robbing and forced to flee. The papal ban was eventually lifted in 1556, by Pope Paul VI.
In England, dissection remained entirely prohibited until the 16th century, when a series of royal edicts gave specific groups of physicians and surgeons some limited rights to dissect cadavers. The permission was quite limited: by the mid 18th century, the Royal College of Physicians and Company of Barber-Surgeons were the only two groups permitted to carry out dissections, and had an annual quota of ten cadavers between them. As a result of pressure from anatomists, especially in the rapidly growing medical schools, the Murder Act 1752 allowed the bodies of all executed criminals to be dissected for anatomical research and education. By the 19th century this supply of cadavers proved insufficient, however, due to both the continuing expansion of medical schools, and the creation of a number of private medical schools, which lacked legal access to cadavers. A thriving black market arose in cadavers and body parts, leading to the creation of an entire profession of body-snatcher, and even more extremely, the infamous 1827 and 1828 Burke and Hare murders, in which 17 people were murdered in order to sell their cadavers to anatomists. The resulting public outcry largely led to the passage of the Anatomy Act 1832, which greatly increased the legal supply of cadavers for dissection. (See also: History of anatomy in the 19th century.)
By the 21st century, the availability of interactive computer programs and changing public sentiment led to renewed debate on the use of cadavers in medical education. The Peninsula College of Medicine and Dentistry in the UK, founded in 2000, became the first modern medical school to carry out its anatomy education without dissection, though most medical schools continue to see experience with actual cadavers as preferable to entirely computer-based education.
Dissections of non-human animals have also been used for educational purposes, often in general science education where the use of human cadavers would not be justified. In the U.S., dissection of frogs became common in college biology classes from the 1920s, and gradually began to be introduced at earlier stages of education. By 1988, an estimated 75–80% of American high school biology students were participating in a frog dissection, with a trend towards introduction in elementary schools. The dissected frogs are most commonly from the Rana genus. Other popular animals for high-school dissection at the time of that survey were, among vertebrates, fetal pigs, perch, and cats; and among invertebrates, earthworms, grasshoppers, crayfish, and starfish.
Controversy over dissection in U.S. high schools became prominent in 1987, when a California student, Jenifer Graham, sued to require her school to let her complete an alternate project. The court ruled that mandatory dissections were permissible, but that Graham could ask to dissect a frog that had died of natural causes rather than one that was killed for the purposes of dissection; the practical impossibility of procuring a frog that had died of natural causes in effect let Graham opt out of the required dissection. The suit also gave considerable publicity to anti-dissection advocates: Graham appeared in a 1988 Apple Computer commercial promoting its "Operation Frog" virtual-dissection software, and the state of California the same year passed a Student's Rights Bill requiring that objecting students be allowed to complete alternative projects. The trend towards students opting out of dissection increased through the 1990s.