We're getting into semantics. Myoblasts fuse satellite cells into existing muscle cells. I said new satellite cells
When muscle is gained through "hyperplasia and hypertrophy," it means that the muscle mass increases due to both an increase in the size of individual muscle fibers (hypertrophy) and an increase in the number of muscle fibers (hyperplasia) within the muscle itself; essentially, the muscle grows both by getting bigger cells and by creating more cells.
But my point has nothing to do with gaining muscle, I argue you never lose muscle, only atrophy existing muscle. Therefore, any bodybuilder that needs to go off or stop training need not worry about 'losing muscle'. It is impossible.
The satellite cells/muscle cells(we can talk how muscle size increases in another thread,
are permanent, as we agree muscle memory. But you will never lose muscle once gained. So if you need to go off gear, stop training, whatever, you'll start right where you left off, you'll just need to hypertrophy cells, not go through the whole process of fusing satellite cells into exiting muscle fibers.