sentences:  Once the immortal DNA strand is labelled and the adult stem cell has begun or resumed asymmetric divisions, the DNA label is chased out.In symmetric divisions (most mitotic cells), DNA is segregating randomly and the DNA label will be diluted out to levels below detection after five divisions.If, however, cells are using an immortal DNA strand mechanism, then all the labeled DNA will continue to co-segregate with the adult stem cell, and after five (or more) divisions will still be detected within the adult stem cell.