igf1, retaining size?

Ok this is a question that my training partner asked me and i couldnt answer can anyone here?
Q: If you take igf1 it stimulates the production of new cells right? So unlike steroids which cause existing muscle cells to grow igf1 does somthing different, it grows new cells (hopefully nearly all muscle cells). But when you stop taking igf1 do these cells die as quickly as regular cells? have you re-written your natural muscle cell base level and will these cells be replaced with new cells or once they die do they not get replaced??

I diddnt know the answer, but arguably should the new muscle cells add to the base number as a permanent addition then continual igf1 use over many cycles should be able to put you at a base level where your a freaking monster should you choose to train or stop. Sure youre muscle cells will shrink but if you have doubled the number in your body youll still be huge!
Or have i gotten the wrong idea?

AAS do increase IGF-1 levels too, just not to the degree that directly taking LR3 will. IGF-1 recruits satellite cells (muscle stem cells) to mature into muscle cells and become part of muscle fibers. Muscle cells are very long-lived cells. By adding more mature muscle cells, you're increasing your potential for growth. IGF-1 not only increases the number of muscle cells, but it also increases protein synthesis within muscle cells. The "gains" are permanent, in a manner of speaking, because you'll retain the additional potential for growth, but the actual size of the muscle cells will decrease upon ceasing to adequately train/nourish them.

concise and to the point, cheers i gotcha.