Cytological Studies of Tumors, XXVIII
Some experimental studies in two sublines of the Yoshida sarcoma, with special consideration of the derivation of sublines
1960 Volume 25 Issue 1 Pages 69-85
Details
1960 Volume 25 Issue 1 Pages 69-85
Some experimental and cytological studies were undertaken in the hope of making clear the mechanism of the rise and further development of sublines in the neoplastic cell-population. Use was made of two sublines, C and D, of the Yoshida sarcoma.
1. The transplantability and life span of tumor-bearing animals differ by rat strains or by tumor sublines. Subline C was wholly non-transplantable to Fischer rats, while subline D showed a transplantability at 80 per cent lethal takes to the same strain of rats.
2. The two sublines differ in their chromosome pattern. The modal chromosome number showed a shift with an increase in frequency of the stem-cells having the modal number of 39 with the accretion of transfer generations in both sublines.
The stemline cells of both tumor lines are clearly distinguishable from each other by their specific ideograms: the stem-cells of subline C have three V-shaped chromosomes of outstandingly large size thereby differing from subline D which contains four such V-shaped elements.
The 4V-type cells rarely occur in subline C, and differ in chromosome constitution from those in subline D. The same situation was found to occur in the 3V-type and 2V-type cells occurring in subline D.
The 2V-type cells occur in subline C at 215th generation, and possess a definite chromosome constitution forming a stemline of cells.
3. Double inoculation experiments with the two sublines produced results showing that there occurs co-existence of the two sublines in the same host without any visible damage to the tumor cells. The 4V-type cells of subline D are generally outnumbered by the 3V-type cells of subline C in the mixed cell-population. The results of selection experiments suggest that though the 3V-type cells usually surpass the 4V-type cells in the mixed cell-population the latter cells tend to displace the 3V-type cells under the influence of a certain selective pressure.
On the basis of the above described experiments and cytological observations, the possible mechanism of the rise and development of tumor sublines were discussed.
