I found this discovery very interesting and dont know why it hasn't been done before.
Being able to watch everything in real time, without having to dissect.

Masayuki Sumida, a professor at the Institute for Amphibian Biology at Japan's Hiroshima University, bred the frog to be a humane learning
tool.
"You can watch organs of the same frog over its entire life, as you don't have to dissect it," Sumida told the news agency Agence France-Presse.
The scientist announced his research last week at an academic meeting.

Also people that thought it is cruel to do such a thing, suggest building a computer simulation as an alternative, is this possible to assume what
will happen based on data?

Dissecting animals for science has sparked controversies worldwide, even prompting some companies to create computer simulations as cruelty-free
alternatives.
Source.
[edit on 30-9-2007 by Denied]