[eli5] Why can cyst grow organs like teeth, eyes and hair but if the original organ is lost it can never grow back?


Dermoid Cysts are known to grow different types of nonfunctioning organs yet it shows it’s possible for the body to still grow new organs.

what is preventing the body to heal major disabilities like a loss of an eye?

In: 12

The thing you are talking about is a teratoma. It is one thing to grow a few simple types of tissue in a jumbled up, incoherent mass. But it’s a totally different thing to grow actual complex organs in exactly the right way. When we develop as embryos, there is a hugely complex signaling process between all the different cells to turn genes on and off in order to get everything to grow in the right place at the right time. Once we are fully developed, there is no way that all of those signals can happen in the right way to regrow a complex organ. In many cases, the cells that generate new tissue types, called stem cells, simply are no longer around

Teratomas are specifically tumors of the germ cells found in the testes and ovaries. Because these cells are pluripotent and able to turn into other types of cells, tumors of them can contain tissues from other cell types. The main reason why your body can’t regrow lost parts (in most cases) is because most cells are somatic and therefore incapable of differentiating to create new tissues.