For thousands of years humans have used embalming methods to preserve dead bodies. But nothing compares with Russia's 90-year-old experiment to preserve the body of Vladimir Lenin, communist revolutionary and founder of the Soviet Union. Generations of Russian scientists have spent almost a century fine-tuning preservation techniques that have maintained the look, feel and flexibility of Lenin's body. This year Russian officials closed the Lenin Mausoleum in Moscow's Red Square so that scientists could prepare the body for public display again in time for the Soviet leader's 145th birthday anniversary today.

The job of maintaining Lenin's corpse belongs to an institute known in post-Soviet times as the Center for Scientic Research and Teaching Methods in Biochemical Technologies in Moscow. A core group of five to six anatomists, biochemists and surgeons, known as the "Mausoleum group," have primary responsibility for maintaining Lenin's remains. (They also help maintain the preserved bodies of three other national leaders: the Vietnamese leader Ho Chi Minh and the North Korean father–son duo of Kim Il-sung and Kim Jong-il, respectively.) The Russian methods focus on preserving the body's physical form—its look, shape, weight, color, limb flexibility and suppleness—but not necessarily its original biological matter. In the process they have created a "quasibiological" science that differs from other embalming methods. "They have to substitute occasional parts of skin and flesh with plastics and other materials, so in terms of the original biological matter the body is less and less of what it used to be," says Alexei Yurchak, professor of social anthropology at the University of California, Berkeley. "That makes it dramatically different from everything in the past, such as mummification, where the focus was on preserving the original matter while the form of the body changes," he adds.

Yurchak has been writing a book describing the history of Lenin's body, the history of the science that arose around it, and the political role that the body and science have played in the Soviet and post-Soviet eras. Much of his material comes from original interviews with Russian researchers working at the "Lenin Lab" (Yurchak's nickname for the institute). He has already published a paper on this project in the journal Representations, and previously published a book, "Everything Was Forever, until It Was No More: The Last Soviet Generation."

When Lenin died in January 1924, most Soviet leaders opposed the idea of preserving his body beyond a temporary period of public display. Many envisioned a burial in a closed tomb on Moscow's Red Square. But the cold winter kept Lenin's publicly displayed corpse in fair condition for almost two months as huge crowds waited to pay their respects. That also gave the leaders time to reconsider the idea of preserving the body for a longer period. To avoid any association of Lenin's remains with religious relics, they publicized the fact that Soviet science and researchers were responsible for preserving and maintaining it.

The leaders eventually agreed to try an experimental embalming technique developed by anatomist Vladimir Vorobiev and biochemist Boris Zbarsky. The first embalming experiment lasted from late March to late July in 1924. Such an effort was complicated by the fact that the physician who carried out Lenin's autopsy had already cut the body's major arteries and other blood vessels. An intact circulatory system could have helped deliver embalming fluids throughout the body.

Lenin Lab researchers eventually developed microinjection techniques that used single needles to deliver embalming fluids to certain bodily parts, preferentially places where cuts or scars from past treatments already existed, Yurchak says. They also created a double-layered rubber suit to keep a thin layer of embalming fluid covering Lenin's body during public display; a regular suit of clothes fits over the rubber suit. The body gets reembalmed once every other year; a process that involves submerging the body in separate solutions of glycerol solution baths, formaldehyde, potassium acetate, alcohol, hydrogen peroxide, acetic acid solution and acetic sodium. Each session takes about one and a half months.

Such painstaking maintenance goes above and beyond common embalming methods used to preserve bodies for funerals and medical education. "Most embalming uses a mix of formaldehyde and alcohol or water, which is called formalin," says Sue Black, director of the Center for Anatomy and Human Identification at the University of Dundee in Scotland. "This has good preservation qualities and has good antifungal properties. Bodies embalmed in this way have a shelf life of tens of years."

Both conventional embalmers and the Lenin Lab face several common challenges, Black explains. Bodies must be kept from drying out so that they don't mummify. Heavy use of formalin can also turn human tissue the color of "canned tuna fish," which is why funeral embalmers use colorants in their embalming fluids to make the recently deceased look a healthy pink. Funeral embalmers also apply cosmetics for temporary funeral displays prior to burial.

But bodies preserved in formalin become discolored, stiff and fragile over the long run. A modern alternative called the Thiel soft-fix method combines a different mix of liquids—including nitrate salts—to maintain the natural color, feel and flexibility of the tissues. Such a method is useful for medical education and training. "Plastination," a technique popularized by Body Worlds exhibits around the world, replaces all the liquid in bodies with a polymer to transform bodies into hard, static sculptures frozen in time.

Although such modern approaches were not available to the Lenin Lab, a technique such as plastination would not have been acceptable in any case, because it creates unnatural stiffness in preserved bodies. To maintain the precise condition of Lenin's body, the staff must perform regular maintenance on the corpse and sometimes even replace parts with an excruciating attention to detail. Artificial eyelashes have taken the place of Lenin's original eyelashes, which were damaged during the initial embalming procedures. The lab had to deal with mold and wrinkles on certain parts of Lenin's body, especially in the early years. Researchers developed artificial skin patches when a piece of skin on Lenin's foot went missing in 1945. They resculpted Lenin's nose, face and other parts of the body to restore them to their original feel and appearance. A moldable material made of paraffin, glycerin and carotene has replaced much of the skin fat to maintain the original "landscape" of the skin.

At the height of activity from the 1950s to the 1980s, the lab employed up to 200 people who did research on subjects ranging from the aging of skin cells to skin transplantation methods, Yurchak says. The institute temporarily lost government funding in the 1990s after the fall of the Soviet Union, but survived on private contributions until government money returned at more modest levels.

During his book research, Yurchak discovered that the Lenin Lab's efforts have even led to spinoff medical applications. One technique influenced Russian development of special equipment used to keeping the blood flowing through donor kidneys during transplantation. In another case veteran lab researcher Yuri Lopukhin and several colleagues developed a "noninvasive three-drop test" to measure cholesterol in skin tissue in the late 1980s. The Russian invention eventually received a patent in 2002 and was commercialized by the Canadian company PreVu as "the world's first and only noninvasive skin cholesterol test" for patient home care. That's one legacy of Lenin that neither the Soviets nor the West could have imagined a century ago.