Cytogenetic analysis of cell lines derived from metastases of a mammary carcinoma in a dog.

Three cell lines derived from two metastases of a mammary carcinoma in a female dog were analyzed cytogenetically. All three cell lines showed a modal chromosome number of 76, with ranges of 74-77, 72-78, and 73-78. A biarmed chromosome in addition to the X chromosomes was observed in all cells of one cell line, and in a part of the cells of the other two cell lines. Results of banding analyses indicated that this chromosome was identical in the three cell lines, and can thus be considered a clonal marker. Additional biarmed chromosomes have not been reported previously from mammary tumor cells, although their presence is rather common in other canine neoplasms.