The Amazing Colossal Man1957

[Dr. Lindstrom explains to Carol that Glenn's heart isn't growing as fast as the rest of his body]

Dr. Paul Linstrom:
Now, the reason for this is rather technical, Carol, but to give you a simplified layman's explanation, it might be explained that, since the heart is made up of a *single* cell for all practical purposes, instead of millions of cells like the rest of the organs of the body, it's reacting in an entirely different manner to this unknown stimulus or forces behind this whole thing.