Table 3.

The effect of injecting female B6A mice with estrogen at 5–7 days of age on thymocyte and splenocyte numbers at adulthood.

Age and Treatment	Thymocytes × 106	Splenocytes × 106
60-day-old, vehicle-injected [8]a	72.5 ± 12.0b	-----
60-day-old, estrogen-injected [14]	43.0 ± 4.8*	-----
100-day-old, vehicle-injected [10]	122.6 ± 19.1	22.0 ± 3.7
100-day-old, estrogen-injected [14]	57.0 ± 7.8**	52.5 ± 5.4*
150-day-old, vehicle-injected [18]	-----	20.4 ± 1.6
150-day-old, estrogen-injected [27]	-----	50.2 + 5.8***

Beginning at 5 days of age, mice were given 3 daily sc injections of 10 μl sesame oil: ethanol (9:1; v:v) {vehicle), with and without 20 μg estradiol-17β. In one study the mice were killed at 60 days of age, thymuses removed, and thymocytes visualized under a light microscope using the Trypan Blue exclusion test and counted in a hemocytometer. In a second study, the mice were killed at 100 days of age, and spleens also removed, and both splenocytes and thymocytes isolated and counted. In a third study, the mice were killed at 150 days of age and only splenocytes were counted.

^aNumber of animals in each group.

^bMean ± S.E.M.

*Significant at p < .05. **Significant at p < .01. ***Significant at p < .001.