Double minute chromosomes are not centromeric regions of the host chromosomes.

Abstract

The SEWA ascites tumor of the mouse contains, in addition to the ordinary chromosomes, a varying number of minute chromatin bodies, called double minutes (dms). Among 394 cells, 43 were without dms, the others had from 1 to 300 dms. The appearance of the dms suggested that they were acentric, which was also supported by the finding that even the largest dms, which were spheres with a diameter larger than the ordinary chromatid breadth, exhibited no C-heterochromatin in Hoechst 33258 fluorescence nor in C-banding with the BSG technique. The conclusion was that the dms of the SEWA tumor have not originated from centromeric regions of ordinary mouse chromosomes.