Eli5: if our bodies are able to form entire human beings from scratch, why can’t it grow back organs that have been amputated?
In: Biology
Because you don’t want a random liver growing out of your elbow.
Growth and differentiation happen under carefully programmed conditions and cells actually “talk” to each other through various signaling to find their position/identity. They don’t have a top down map of the body, so they find their position relative to the signals put out by neighboring tissues, and most of that natural programming is calibrated for the first few weeks of fetal development, or other specific stages of growth.
When the systems controlling/restraining that programming shut down you get cancers.
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