> It’s not that obvious, as the brain grows, certain kind of cells die off and never come back. I'm not sure what difference that would make. Those brain cells

> It’s not that obvious, as the brain grows, certain kind of cells die off and never come back. I'm not sure what difference that would make. Those brain cells (and all the other brain cells that don't die off) were still formed by successive divisions of the single cell that resulted from sperm meeting egg. Therefore, that original cell is capable of producing any cell type found in the body.