[Studies on the tissue culture of murine sarcoma (Dunn sarcoma)--a fix cell line established in vitro (DSK) and its cytokinetic findings (author's transl)].

Dunn osteosarcoma, transplanted successively from the original spontaneous murine osteosarcoma, was cultured for generations and serial changes of cultured cells were observed morphologically and also from the view points of chromosomes and cytokinetics. 1) In the early generations of subculture, the cultured cells were predominantly of spindle shape, proliferating in a mesh-like pattern. However, with generations the epitheloid cells became dominant with a slight increase in their proliferating rate, and from 16th generation thereafter, the cellular pattern became almost uniform. The nuclei, being in the center of the cytoplasm, varied in their size and number, and several mitoses were also noted. In the 8th and 9th generations, the multinucleated giant cells were greatest in their size, and their nuclei were most numerous. 2) The cells of each generation, inoculated into the mice, developed tumors in the mice with the same histological appearance as that of original tumors. From the 17th generation thereafter, these inoculations (in vivo back inoculation) were constantly successful in producing tumors. Meanwhile, the cells of the tumor induced by in vivo back inoculation could be cultured, and showed the same morphological patterns as that of the serially cultured cells. 3) The chromosomes of the cultured cells were prepared by treating the tissue with colchicine followed by 0.2% hypotonic saline. From the primary culture to the first ten generations, the mode of the chromosome number varied from diploidy to high diploidy, while it became stable in high diploidy from 16th generation thereafter. The shapes of the chromosomes were various, and there were a few bar-shaped chromosomes. No constant marker chromosome was detectable. 4) The mouse spleen cells, cultured with the inactivated cultured tumor cells were activated by the target, recognizing the tissue specific transplantation antigen of the target. Considering these findings, this series of tissue culture is regarded as a fixed cell line. Therefore, it is concluded that an experimental system of Dunn osteosarcoma has been established in vitro, and it could be named as DSK (Dunn sarcoma in vitro, KITASATO) by the author. The duration of cell cycle of DSK, using the cumulative labeling method, is 11 hours, which is about two hours shorter than that of in vivo.