Abstract
Some cytological observations were undertaken with special regard to the cellular interaction between HeLa and L cells cultured in the same flask. HeLa cells here under study were characterized by a typical epithelial-like growth pattern with a distinct modal chromosome number at 67, whereas L cells were fibroblast-like in general morphology and showed 66 chromosomes as a modal number. As shown in Figs. 1 and 2, both cell lines showed specific karyotypes clearly distinguishable from each other. Based on the difference in karyotype as well as in general morphology occurring in both cell lines, it was possible to investigate the frequency-distribution of HeLa and L cells in mixed cell populations.
Simultaneous inoculation-experiments with the equal number of cells from the two cell lines resulted in that L cells showed a gradual disappearance from the mixed cell population within 30 days after mixing, and that the population was completely replaced by HeLa cells. In the early mixed cultures many abnormal L cells occurred, due probably to the effect of the co-existence of HeLa cells. The most prominent abnormality was the formation of cytoplasmic blebs in relatively round and pycnotic L cells.
In the inoculation of HeLa cells in pre-existence of L cells, no such abnormality occurred in L cells, and cells of the latter type gradually disappeared from the mixed cell population.
In virtue of the available data obtained, the reciprocal interaction between the HeLa and L cells were discussed, particularly on possible factors in relation to their growth patterns. Further, some comment pertaining to the cellular contamination in tissue culture was given.
No evidence was provided, of “cell hybrid” formation between HeLa and L cells, so far as the scope of the present study is concerned.
