Immortalized, premalignant epithelial cell populations contain long-lived, label-retaining cells that asymmetrically divide and retain their template DNA

Table 8 Percentage of cells expressing a PR and ³H-TdR double-label per field of view found in the glands and mammary fat pads of Balb/C female mice that were either intact or implanted with immortalized, premalignant cells

	Percentage (%)
Intact (control) gland:Implant group	Nulliparous	Pregnant
Intact:NSP2	0.20:0.02	0.04:0.006
Intact:NSP3	0.0:0.05	0.17:0.0
Intact:SP3	0.10:0.0	0.07:0.02

The number of cells expressing a PR and ³H-TdR (double-label) were counted in three random fields of view (400× magnification). In addition, the total number of cells in three random fields of view was determined (>1000 cells total counted; 400× magnification). The total number of cells expressing a PR and ³H-TdR double-label was then divided by the total number of cells in a field of view, and the percentage of cells expressing a PR and ³H-TdR double-label per field of view was obtained.

ISSN: 1465-542X