Table 2

Percentages of LREC within the receptor positive cell population

Time point

% ER-α-positive LREC population^a

% ER-α-positive total population^a

Ratio of % ER-α-positive LREC to total % ER-α-positive population^a

% PR-positive LREC population^a

% PR-positive total population^a

Ratio of PR-positive LREC to total PR-positive population^a

Non-pregnant

11.4 ± 3.2

16.1 ± 2.45

11.4/16.1 = 0.7081

14.1 ± 4.1

21.9 ± 5.96

14.1/21.9 = 0.6438

Group 1

10.1 ± 2.4

20.6 ± 5.92

10.1/20.6 = 0.4903

19.3 ± 5.9

22.4 ± 4.20

19.3/22.4 = 0.8616

Group 2

12.8 ± 7.9

16.1 ± 7.74

12.8/16.1 = 0.7950

18.0 ± 7.4

19.5 ± 4.23

18.0/19.5 = 0.9424

Group 3

13.7 ± 5.3

20.1 ± 5.64

13.7/20.1 = 0.6816

18.3 ± 10.1

14.3 ± 4.92^*†

18.3/14.3 = 1.2797

Group 4

18.3 ± 8.1

6.62 ± 2.17*

18.3/6.62 = 2.7644

19.3 ± 9.4

6.5 ± 1.47^*†

19.3/6.5 = 2.9692

One thousand cells were counted in mammary gland sections stained for 5BrdU and ER-α or 5BrdU and PR. ([³H]-thymidine and steroid receptors were counted for Group 4). Group 1 tissue was collected at day 3 of pregnancy, Group 2 tissue was collected at day 4 of pregnancy, Group 3 tissue was collected at day 6 of pregnancy, and Group 4 tissue was collected at day 13 of pregnancy after second 5BrdU dose at day 4. Values are expressed as mean ± standard deviation, or as %/% = ratio. ^aDouble positive for 5BrdU and receptor/total receptor positive. *P < 0.05 versus virgin control; ^†P < 0.05 versus group 1. 5BrdU, 5-bromodeoxyuridine; ER, estrogen receptor; LREC, label-retaining epithelial cells; PR, progesterone receptor.

Booth et al. Breast Cancer Research 2008 10:R90   doi:10.1186/bcr2188