How do tumors grow things like eyes, teeth, brain tissue and organs when the human body often can’t grow those by itself?

Question

There was a post about a woman who grew a “homonculus tumor”, with brain tissue, teeth, a spinal nerves and other organs. But how? Human bodies can’t grow those things after birth, AFAIK. For example, once your adult teeth are in, that’s it. So how are tumors able to do this? Are the cells in tumors different from those found normally in human body?

In: 1354

Answer 1

Every cell in your body has the same set of instructions for making eyes, teeth, hair, etc. However, a cell will turn off the ones that it doesn’t need for its function at different points at development. Tumors turn these instructions back on.