Okay, I made a statement without doing full research. I was wrong there.

But yes, a fetus develops, it is originally made up of stem cells untill they reproduce to a cluster of 16, 8 making up an outer wall and 8 an inner cluster. The exterior 8 then develop into our skin and other sensory receptors, and the inner 8 develop into internal organs. It is pretty long and drawn out process but the cells are originally uniform in type but specify.

Unlike a tumor which is a rampant mutation in a single cell the develops into a cluster of cells with no differentiating charateristics.