(CNN) -

The 2012 Nobel Prize for Physiology or Medicine was awarded Monday to Sir John B. Gurdon and Shinya Yamanaka for work that revolutionized the understanding of how cells and organisms develop.

The Nobel Assembly's announcement at the Karolinska Institute in Stockholm, Sweden, is the first for what will be a series of prizes announced this week. The Norwegian Nobel committee will announce the most anticipated of the annual honors -- the Nobel Peace Prize -- on Friday in Oslo, Norway.

Gurdon, 79, of Dippenhall, England, and Yamanaka, 50, of Osaka, Japan, share the prize jointly for their discovery that "mature, specialised cells can be reprogrammed to become immature cells capable of developing into all tissues of the body," according to the Nobel Assembly, which consists of 50 professors at the Karolinska Institute.

Gurdon discovered in 1962 that the cells are reversible in an experiment with an egg cell of a frog. Yamanaka discovered more than 40 years later how mature cells in mice could be reprogrammed to become immature stem cells "that are able to develop into all types of cells in the body," the assembly said in a statement.

"These groundbreaking discoveries have completely changed our view of the development and cellular specialisation. We now understand that the mature cell does not have to be confined forever to its specialised state," the Nobel Assembly said.

"Textbooks have been rewritten and new research fields have been established. By reprogramming human cells, scientists have created new opportunities to study diseases and develop methods for diagnosis and therapy.

Separated by more than 40 years, the work of Gurdon and Yamanaka led to a practical medical use for stem cell research that sidesteps the main argument by anti-abortion opponents.

Now embryonic-like stem cells can be created in the laboratory from adult cells of the same organism, rather than using aborted fetuses or embryos, explained Visar Belegu, a stem cell researcher at the Hugo W. Moser Research Institute, part of the Kennedy Krieger Institute in Baltimore.

Gurdon pioneered cloning through cell reproduction in a tadpole in 1962. In 2006, Yamanaka figured out how to reprogram mature cells so that they revert to their primitive state as "induced pluripotent stem cells," or iPS cells, capable of developing into any part of the body, Belegu said.

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Nobel Prize season opens with medicine award