Smith J R, Hayflick L
J Cell Biol. 1974 Jul;62(1):48-53. doi: 10.1083/jcb.62.1.48.
The doubling potential of several hundred clones derived from WI-38 and WI-26 cell cultures has been determined. Clones were isolated at various population doubling levels (PDLs) during the finite in vitro life-span of the mass (uncloned) cultures. In all cases, there was a large variation in population doubling potential (or life-span) among the clones isolated from a single mass culture. When clones were isolated from mass cultures which had undergone eight or nine population doublings, only about 50% of the clones were capable of more than eight population doublings. This percentage was further reduced when clones were isolated from mass cultures at higher PDLs. Mass cultures appear to be composed of two subpopulation classes: one with a low population doubling potential, and the other with a higher population doubling potential. Nevertheless, the highest doubling potential observed in clones isolated from any single culture was about the same as the doubling potential of the mass culture from which single cells were taken.
已测定了源自WI - 38和WI - 26细胞培养物的数百个克隆的倍增潜力。在群体（未克隆）培养物有限的体外寿命期间，在不同的群体倍增水平（PDL）下分离克隆。在所有情况下，从单个群体培养物中分离出的克隆之间，群体倍增潜力（或寿命）存在很大差异。当从经历了八或九次群体倍增的群体培养物中分离克隆时，只有约50%的克隆能够进行超过八次群体倍增。当从更高PDL的群体培养物中分离克隆时，这一百分比会进一步降低。群体培养物似乎由两个亚群组成：一个群体倍增潜力低，另一个群体倍增潜力高。然而，从任何单个培养物中分离出的克隆中观察到的最高倍增潜力与从中获取单细胞的群体培养物的倍增潜力大致相同。
