Figure 2

Karyotypes of two invasive rat mammary carcinomas and of four neoplastic clones evolved from non-clonal hyperplasias in vitro. The karyotypes of the two rat mammary carcinomas RMT 47–3 (A) and 37–2 (B) were prepared from short-term cultures of the two carcinomas treated with colcemid for several hours following published procedures [17],[49]. Prior to karyotyping the metaphase chromosomes were hybridized with DNA probes carrying chromosome-specific fluorescent colors (Methods). The chromosomes were then arranged into conventional karyotypes with a computer-assisted Zeiss microscope [17],[49]. The karyotypes of the four clonal neoplasias RMT-CN 65 (C), RMT-CN 58 (D), RMT-CN 54 (E) and RMT-CN 61 (F), which had evolved spontaneously from cultures of preneoplastic hyperplasias propagated in vitro, were prepared as described for the two carcinomas.