Autoradiographic study on the localization of estradiol-17beta in neonatal mouse uterus and cervix

The uptake of 3H-estradiol-17beta in the neonatal mouse uterus and cervix has been studied by an autoradiographic method. When the radioactive hormone is administered in vivo and in vitro, grains are found to be concentrated above the nuclei both in the uterine and cervical epithelium and stroma. Grain counts revealed that the nuclear concentration of grains is higher at 4 h than at 2 h after isotope injection. The cervical epithelium has a higher nuclear concentration than the uterine epithelium both in vivo and in vitro. In the stroma, this situation is reversed except after in vitro treatment of the tissues. In the cervix, more of the hormone seems to be located within the nucleus while in the uterus a higher proportion of the grains are found in the vicinity of the nuclear periphery. Although the nuclear concentration of grains is higher at 4 h than at 2 h, the number of grains above the sections is lower at 4 h. Both in vivo and in vitro, the number of grains is higher above the stromal than above the epithelial compartments of the uterus and cervix. Five days old animals showed the same labeling pattern. The differences in uptake and distribution of 3H-estradiol are discussed in relation to other known differences in the hormone responsiveness in these tissues.