Table 5.

Percentage of cells expressing ER-α 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

	Percent (%)
Intact (control) gland:Implant group	Nulliparous	Pregnant
Intact:NSP2	20.4:5.8	7.5:7.5
Intact:NSP3	21.5:6.1	7.4:5.9
Intact:SP3	16.4:2.3	6.8:6.4

The number of cells expressing ER-α 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 expressing ER-α was then divided by the total number of cells in a field of view, and the percentage of cells expressing ER-α per field of view was obtained.