Table 2. Uptake values of ^99mTc(I)-estradiol-pyridin-2-yl hydrazine derivative throughout the estrous cycle.

Reproductive organs, mammary glands, bone, blood and muscle of 8-10 weeks old female C57Bl/6 mice in defined stages of estrous cycle were evaluated. All uptake values are expressed as % ID/g and were determined from biodistribution studies. Data represent the mean value ± SEM from 4 determinations.

Organ	Estrus	Estrus (block)a	Metestrus	Metestrus(block)a	Diestrus	Diestrus (block)a
Blood	2.30 ± 1.02	1.92 ± 0.95	2.50 ± 0.88	2.54 ± 1.63	2.70 ± 0.12	2.42 ± 0.24
Bone	0.22 ± 0.06	0.17± 0.02	0.15 ± 0.04	0.24 ± 0.10	0.14 ± 0.01	0.17 ± 0.02
Muscle	0.09± 0.01	0.09 ± 0.02	0.11 ± 0.01	0.08 ± 0.04	0.15 ± 0.02	0.13 ± 0.02
Mammaryb,c	0.22 ± 0.02	0.08 ± 0.01	1.31 ± 0.13	0.19 ± 0.02	3.11 ± 0.24	0.78 ± 0.06
Uterusb, c	0.55 ± 0.02	0.36 ± 0.02	0.79 ± 0.09	0.48 ± 0.04	1.44 ± 0.07	0.63 ± 0.04
Ovariesb, d	0.60 ± 0.06	0.24 ± 0.03	0.76 ± 0.04	0.39 ± 0.05	1.24 ± 0.22	0.60 ± 0.05

^aReceptor blocking studies were performed by co-injecting 5 μg 17β-estradiol with the radiotracer.

^bUptake values (n ≥ 4) in each phase of the estrous cycle are significantly different ( p < 0.05) from the values in the same phase of the estrous cycle when compared to uptake in the presence of 5 μg co-injected17β-E2.

^cUptake values (n ≥ 4) in each phase of the estrous cycle are significantly different ( p < 0.05) from one another.

^dUptake values (n ≥ 4) in each phase of the estrous cycle are not significantly different ( p < 0.05) from one another comparing the estrus and metestrus, or the metestrus and diestrus. However, the values are significantly different comparing estrus and diestrus.