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

Table 2 Percentage of cells expressing either a 5-BrdU or ³H-TdR single 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 (%)
	Nulliparous		Pregnant
Intact (control) gland:Implant group	5-BrdU	³ H-TdR	5-BrdU	³ H-TdR
Intact:NSP²	13.0:13.0	8.2:14.3	0.6:6.8	5.2:1.9
Intact:NSP³	23.8:19.7	3.5:2.0	0.8:3.5	2.7:8.7
Intact:SP³	12.0:4.4	4.8:0.4	0.1:4.0	1.9:6.5

The number of cells labeled with either 5-BrdU or ³H-TdR was 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 labeled with either 5-BrdU or ³H-TdR was then divided by the total number of cells in a field of view, and the percentage of cells labeled with either 5-BrdU or ³H-TdR per field of view was obtained.

ISSN: 1465-542X